RD Sharma - Mathematics

Book: RD Sharma - Mathematics

Chapter: 7. Values of Trigonometric Functions at Sum of Difference of Angles

Subject: - Class 11th

Q. No. 33 of Exercise 7.1

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If , then show that sin α + cos α = cos x.


Dividing numerator And denominator on RHSBy cos α,

We know that

Consider sin α + cos α,

We know that sin(A +B) = sinA cosB + cosA sinB And cos(A +B) = cosA cosB - sinA sinB

= √2 cos x

sin α + cos α = √2 cos x

Hence proved.

Chapter Exercises

More Exercise Questions


If SinA = 1/2, cosB = , where π/2<A < π And 0 <B < π/2, find the following:

(i) tan(A +B)(ii) tan(A -B)