Given A = 60° and B = 30°, prove that :
cos (A - B) = cos A cos B + sin A sin B

Question

Given A = 60° and B = 30°, prove that : cos (A - B) = cos A cos B + sin A sin B

KnowledgeBoat · Accepted Answer

cos (A - B) = cos A cos B + sin A sin B L.H.S. = cos (A - B) = cos (60° - 30°) = cos 30° = R.H.S. = cos A cos B + sin A sin B = cos 60° cos 30° + sin 60° sin 30° ∴ L.H.S. = R.H.S. Hence, cos (A - B) = cos A cos B + sin A sin B.

Mathematics

Given A = 60° and B = 30°, prove that :
cos (A - B) = cos A cos B + sin A sin B

Trigonometric Identities

Related Questions

Given A = 60° and B = 30°, prove that :
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Mathematics

Given A = 60° and B = 30°, prove that :cos (A - B) = cos A cos B + sin A sin B

Trigonometric Identities

Related Questions

Given A = 60° and B = 30°, prove that :sin (A + B) = sin A cos B + cos A sin B

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Given A = 60° and B = 30°, prove that :
cos (A - B) = cos A cos B + sin A sin B

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sin (A + B) = sin A cos B + cos A sin B

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