let ABC be a right triangle at A such that $BC=2AB$. Find $angle ACB$












1












$begingroup$


So let $triangle ABC$ be a right triangle at vertex $A$ such that $BC=2AB$. Find the $angle ACB$



How can I find that angle without using cosine, sine and other things?



Since I've already figure out how to find it using cos: here's my approach:



We denote $angle ABC$ as $alpha$ so $$cosalpha=frac{AB}{BC}=frac{AB}{2AB}=frac{1}{2}$$



We do $cos^{-1}$ to find $angle ABC$ then we do $90^circ-angle ABC$ to find $angle ACB$.



So I'm looking for alternative way.



Thanks!










share|cite|improve this question











$endgroup$

















    1












    $begingroup$


    So let $triangle ABC$ be a right triangle at vertex $A$ such that $BC=2AB$. Find the $angle ACB$



    How can I find that angle without using cosine, sine and other things?



    Since I've already figure out how to find it using cos: here's my approach:



    We denote $angle ABC$ as $alpha$ so $$cosalpha=frac{AB}{BC}=frac{AB}{2AB}=frac{1}{2}$$



    We do $cos^{-1}$ to find $angle ABC$ then we do $90^circ-angle ABC$ to find $angle ACB$.



    So I'm looking for alternative way.



    Thanks!










    share|cite|improve this question











    $endgroup$















      1












      1








      1





      $begingroup$


      So let $triangle ABC$ be a right triangle at vertex $A$ such that $BC=2AB$. Find the $angle ACB$



      How can I find that angle without using cosine, sine and other things?



      Since I've already figure out how to find it using cos: here's my approach:



      We denote $angle ABC$ as $alpha$ so $$cosalpha=frac{AB}{BC}=frac{AB}{2AB}=frac{1}{2}$$



      We do $cos^{-1}$ to find $angle ABC$ then we do $90^circ-angle ABC$ to find $angle ACB$.



      So I'm looking for alternative way.



      Thanks!










      share|cite|improve this question











      $endgroup$




      So let $triangle ABC$ be a right triangle at vertex $A$ such that $BC=2AB$. Find the $angle ACB$



      How can I find that angle without using cosine, sine and other things?



      Since I've already figure out how to find it using cos: here's my approach:



      We denote $angle ABC$ as $alpha$ so $$cosalpha=frac{AB}{BC}=frac{AB}{2AB}=frac{1}{2}$$



      We do $cos^{-1}$ to find $angle ABC$ then we do $90^circ-angle ABC$ to find $angle ACB$.



      So I'm looking for alternative way.



      Thanks!







      geometry






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      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Jan 27 at 12:43









      Larry

      2,53531131




      2,53531131










      asked Mar 29 '14 at 13:09









      user138849user138849

      153




      153






















          1 Answer
          1






          active

          oldest

          votes


















          0












          $begingroup$

          Hint: take an equilateral triangle and draw one of the altitudes. Remember this altitude is also an angle bisector and a median, so...






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I don't understand those terms, could you clarify a bit more please sir :)
            $endgroup$
            – user138849
            Mar 29 '14 at 13:40










          • $begingroup$
            Altitude=height=segment of straight line from a vertex to the opposite side (a cevian) which is perpendicular to that side. What else isn't clear, @user138849 ?
            $endgroup$
            – DonAntonio
            Mar 29 '14 at 13:42












          • $begingroup$
            I'm not a native english speaker so I don't know what equilateral triangle means, bisector, median
            $endgroup$
            – user138849
            Mar 29 '14 at 13:52










          • $begingroup$
            Then I can't help you, @user138849...I don't even know what your mother tongue is. If you ask in english then try to look for the corresponding terms in english.
            $endgroup$
            – DonAntonio
            Mar 29 '14 at 13:56






          • 1




            $begingroup$
            ookay i understand thanks anyway
            $endgroup$
            – user138849
            Mar 29 '14 at 13:57











          Your Answer





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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          0












          $begingroup$

          Hint: take an equilateral triangle and draw one of the altitudes. Remember this altitude is also an angle bisector and a median, so...






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I don't understand those terms, could you clarify a bit more please sir :)
            $endgroup$
            – user138849
            Mar 29 '14 at 13:40










          • $begingroup$
            Altitude=height=segment of straight line from a vertex to the opposite side (a cevian) which is perpendicular to that side. What else isn't clear, @user138849 ?
            $endgroup$
            – DonAntonio
            Mar 29 '14 at 13:42












          • $begingroup$
            I'm not a native english speaker so I don't know what equilateral triangle means, bisector, median
            $endgroup$
            – user138849
            Mar 29 '14 at 13:52










          • $begingroup$
            Then I can't help you, @user138849...I don't even know what your mother tongue is. If you ask in english then try to look for the corresponding terms in english.
            $endgroup$
            – DonAntonio
            Mar 29 '14 at 13:56






          • 1




            $begingroup$
            ookay i understand thanks anyway
            $endgroup$
            – user138849
            Mar 29 '14 at 13:57
















          0












          $begingroup$

          Hint: take an equilateral triangle and draw one of the altitudes. Remember this altitude is also an angle bisector and a median, so...






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I don't understand those terms, could you clarify a bit more please sir :)
            $endgroup$
            – user138849
            Mar 29 '14 at 13:40










          • $begingroup$
            Altitude=height=segment of straight line from a vertex to the opposite side (a cevian) which is perpendicular to that side. What else isn't clear, @user138849 ?
            $endgroup$
            – DonAntonio
            Mar 29 '14 at 13:42












          • $begingroup$
            I'm not a native english speaker so I don't know what equilateral triangle means, bisector, median
            $endgroup$
            – user138849
            Mar 29 '14 at 13:52










          • $begingroup$
            Then I can't help you, @user138849...I don't even know what your mother tongue is. If you ask in english then try to look for the corresponding terms in english.
            $endgroup$
            – DonAntonio
            Mar 29 '14 at 13:56






          • 1




            $begingroup$
            ookay i understand thanks anyway
            $endgroup$
            – user138849
            Mar 29 '14 at 13:57














          0












          0








          0





          $begingroup$

          Hint: take an equilateral triangle and draw one of the altitudes. Remember this altitude is also an angle bisector and a median, so...






          share|cite|improve this answer









          $endgroup$



          Hint: take an equilateral triangle and draw one of the altitudes. Remember this altitude is also an angle bisector and a median, so...







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Mar 29 '14 at 13:24









          DonAntonioDonAntonio

          180k1494233




          180k1494233












          • $begingroup$
            I don't understand those terms, could you clarify a bit more please sir :)
            $endgroup$
            – user138849
            Mar 29 '14 at 13:40










          • $begingroup$
            Altitude=height=segment of straight line from a vertex to the opposite side (a cevian) which is perpendicular to that side. What else isn't clear, @user138849 ?
            $endgroup$
            – DonAntonio
            Mar 29 '14 at 13:42












          • $begingroup$
            I'm not a native english speaker so I don't know what equilateral triangle means, bisector, median
            $endgroup$
            – user138849
            Mar 29 '14 at 13:52










          • $begingroup$
            Then I can't help you, @user138849...I don't even know what your mother tongue is. If you ask in english then try to look for the corresponding terms in english.
            $endgroup$
            – DonAntonio
            Mar 29 '14 at 13:56






          • 1




            $begingroup$
            ookay i understand thanks anyway
            $endgroup$
            – user138849
            Mar 29 '14 at 13:57


















          • $begingroup$
            I don't understand those terms, could you clarify a bit more please sir :)
            $endgroup$
            – user138849
            Mar 29 '14 at 13:40










          • $begingroup$
            Altitude=height=segment of straight line from a vertex to the opposite side (a cevian) which is perpendicular to that side. What else isn't clear, @user138849 ?
            $endgroup$
            – DonAntonio
            Mar 29 '14 at 13:42












          • $begingroup$
            I'm not a native english speaker so I don't know what equilateral triangle means, bisector, median
            $endgroup$
            – user138849
            Mar 29 '14 at 13:52










          • $begingroup$
            Then I can't help you, @user138849...I don't even know what your mother tongue is. If you ask in english then try to look for the corresponding terms in english.
            $endgroup$
            – DonAntonio
            Mar 29 '14 at 13:56






          • 1




            $begingroup$
            ookay i understand thanks anyway
            $endgroup$
            – user138849
            Mar 29 '14 at 13:57
















          $begingroup$
          I don't understand those terms, could you clarify a bit more please sir :)
          $endgroup$
          – user138849
          Mar 29 '14 at 13:40




          $begingroup$
          I don't understand those terms, could you clarify a bit more please sir :)
          $endgroup$
          – user138849
          Mar 29 '14 at 13:40












          $begingroup$
          Altitude=height=segment of straight line from a vertex to the opposite side (a cevian) which is perpendicular to that side. What else isn't clear, @user138849 ?
          $endgroup$
          – DonAntonio
          Mar 29 '14 at 13:42






          $begingroup$
          Altitude=height=segment of straight line from a vertex to the opposite side (a cevian) which is perpendicular to that side. What else isn't clear, @user138849 ?
          $endgroup$
          – DonAntonio
          Mar 29 '14 at 13:42














          $begingroup$
          I'm not a native english speaker so I don't know what equilateral triangle means, bisector, median
          $endgroup$
          – user138849
          Mar 29 '14 at 13:52




          $begingroup$
          I'm not a native english speaker so I don't know what equilateral triangle means, bisector, median
          $endgroup$
          – user138849
          Mar 29 '14 at 13:52












          $begingroup$
          Then I can't help you, @user138849...I don't even know what your mother tongue is. If you ask in english then try to look for the corresponding terms in english.
          $endgroup$
          – DonAntonio
          Mar 29 '14 at 13:56




          $begingroup$
          Then I can't help you, @user138849...I don't even know what your mother tongue is. If you ask in english then try to look for the corresponding terms in english.
          $endgroup$
          – DonAntonio
          Mar 29 '14 at 13:56




          1




          1




          $begingroup$
          ookay i understand thanks anyway
          $endgroup$
          – user138849
          Mar 29 '14 at 13:57




          $begingroup$
          ookay i understand thanks anyway
          $endgroup$
          – user138849
          Mar 29 '14 at 13:57


















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