Samacheer Kalvi 9th Maths Solutions Chapter 6 Trigonometry Ex 6.2

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

Question 1.
Verify the following equalities:
(i) sin² 60° + cos² 60° = 1
(ii) 1 + tan² 30° = sec² 30°
(iii) cos 90° = 1 – 2 sin² 45° = 2 cos² 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 cos³A – 3 cos A, when A = 30°
Solution:
L.H.S = cos 3A = cos 3(30°) = cos 90° = 0
R.H.S = 4 cos³A – 3 cos A = 4 cos³30° – 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°)