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In a triangle triangle ABC if cos C=sinA/2sinB,prove that the triangle is isosceles.

In a triangle triangle ABC  if  cos C=sinA/2sinB,prove that the triangle is isosceles.

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2 Answers

Sunil Raikwar
askIITians Faculty 45 Points
8 years ago
2sinBcosC=sinA
sin(B+C)+sin(B-C)=sinA
sin(180-A)+sin(B-C)=sinA
sinA+sin(B-C)=sinA
sin(B-C)=0
B-C=0
B=C
Thanks & Regards
Sunil Raikwar
askIITians faculty
Manas Satish Bedmutha
22 Points
8 years ago

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