RD Sharma - Mathematics

Book: RD Sharma - Mathematics

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

Subject: - Class 11th

Q. No. 17 of Exercise 7.1

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17

Prove that:

tan 8x – tan6x – tan 2x = tan 8x


tan 6x tan 2x

We have 8x = 6x + 2x


tan 8x = tan(6x + 2x)


We know that



tan8x (1 – tan6x tan2x) = tan6x + tan2x


tan8x – tan8x tan 6x tan2x = tan6x + tan2x


tan8x – tan6x – tan2x = tan8x tan6x tan2x


Hence, proved.


Chapter Exercises

More Exercise Questions

6

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)