RD Sharma - Mathematics

Book: RD Sharma - Mathematics

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

Subject: - Class 11th

Q. No. 8 of Exercise 7.1

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If cosA = –12/13 and cotB = 24/7, where A lies in the second quadrant and B in the third quadrant, find the values of the following:

(i) sin(A +B) (ii) cos(A +B) (iii) tan(A +B)

Given cosA = -12/13 And cotB = 24/7

A lies in second quadrant And B in the third quadrant.

The sine function is positive in the second quadrant and in the third quadrant,Both sine And cosine functions are negative.

We know that


(i) Sin(A +B)

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

(ii) Cos(A +B)

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

(iii) Tan(A +B)

We know that


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)