Question

if cosA=cosB,then prove angle A=angle B.solve no. 6

Answer 1

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Answer 2

● Trigonometry ●

In ∆ABC,

cosA = cosB

To prove : - Angle A = Angle B.

Now,

cosA = AC/AB .......(i)

cosB = BC/AB ......(ii)

Now,

cosA = cosB (Given)

From (i) and (ii),

AC/AB = BC/AB

=> AC = BC

So, Angle A = Angle B (Because, angles opposite to equal sides are equal.)

Hence, proved.