Question

"Question38
If sin A = 60° and B= 30° , verify that: cos (A-B) = cos A cos B + sin A sin B
Chapter6,T-Ratios of particular angles Exercise -6 ,Page number 289"

Answer 1

Hey there! Thanka for the question!

Given,
A = 60° , B = 30°

Now,
cos (A - B) = cosA cos B + sin A sin B.

Substituting A = 60 , B = 30°

cos(60- 30) = cos60 cos30 + sin30 sin60


We know, Trigonometry ratios of particular angles : cos90 = 0 , cos30 = √3/2 , cos60 = 1/2

√3/2 = 1/2 ( √3/2) + (√3/2) ( 1/2)

√3/2 = √3/4 + √3/4

√3/2 = 2 ( √3/4 )

√3/2 = √3/2

Both Sides of the equation are equal.

Hence, We proved and verified that cos(A - B) = cosA cos B + sin A sin B. holds good for A = 60, B = 30°

Answer 2

HEY!!

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