If ∠A and ∠B are acute angles such that cos A = cos B, then show that ∠A = ∠B.
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Solution
∠A and ∠B are acute angles
Cos A = cos B S.T ∠A = ∠B
Let us consider right angled triangle ACB.
We have `cos A = "adjacent side"/"Hypotenuse"`
`= (AC)/(AB)`
`cos B = (BC)/(AB)`
cos A = cos B
`(AC)/(AB) = (BC)/(AB)`
AC = BC
∠A = ∠B
Concept: Trigonometric Ratios and Its Reciprocal
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