If a = 600 and B = 300, Verify That: (Ii) Cos (A – B) = Cos a Cos B + Sin a Sin B - Mathematics

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If A = 600 and B = 300, verify that: 

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

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Solution

cos (A – B) = cos 300 =`sqrt(3)/2`

cos A cos B + sin A sin B = cos 600 cos 300 + sin 600 sin 30

=`( 1/2 xx sqrt(3)/2 + sqrt(3)/2 xx1/2) = (sqrt(3)/4 + sqrt(3)/4) = 2 xx sqrt(3)/4 = sqrt(3)/2`

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

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Chapter 6: T-Ratios of some particular angles - Exercises

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RS Aggarwal Secondary School Class 10 Maths
Chapter 6 T-Ratios of some particular angles
Exercises | Q 15.2

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