Question

If a,b,c are interior angles of triangle And show that,cos^2(a/2)+cos^2(b+c/2)=1

Answer 1

Explanation:

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If in a triangle ABC a Cos*2(c/2)+cos*2(A/2)=3b/2 then the sides a,b,c are

one year ago

Answers : (1)

we know cosC=2cos^2(C/2)-1

so, a(1+cosC)/2+c(1+cosA)/2=3b/2

a+acosC+c+ccosA=3b

a+c+(acosC+ccosA)=3b

Using By projection formula: (acosC+ccosA)=b

a+c+b=3b

a+c=2b

This shows that a,b,c are in A.P.

thank you.