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## Tamilnadu Samacheer Kalvi 9th Maths Solutions Chapter 6 Trigonometry Ex 6.2

Question 1.

Verify the following equalities:

(i) sin^{2} 60° + cos^{2} 60° = 1

(ii) 1 + tan^{2} 30° = sec^{2} 30°

(iii) cos 90° = 1 – 2 sin^{2} 45° = 2 cos^{2} 45° – 1

(iv) sin 30° cos 60° + cos 30° sin 60° = sin 90

Solution:

Question 2.

Find the value of the following:

Solution:

Question 3.

Verify cos 3A = 4 cos^{3}A – 3 cos A, when A = 30°

Solution:

L.H.S = cos 3A = cos 3(30°) = cos 90° = 0

R.H.S = 4 cos^{3}A – 3 cos A = 4 cos^{3}30° – cos 30°

(1) = (2). Hence it is verified.

Question 4.

Find the value of 8 sin 2x cos 4x sin 6x, when x = 15°

Solution:

8 sin 2(15°).cos 4(15°).sin 6(15°)