Identity is always true and is an equation in mathematics. It is like a = a , x = x , n = n and is trivially true like Pythagoras theorem for a right triangle, x2 = y2 + z2 As there are many trigonometric identities, you’ll find these ones in the list too.
| Sin2 a = 1 – cos2 a |
Sin squared x Examples
Q.1: Find the value of sin a if cos a = 3/5?
Solution: Sin2 a = 1 – cos2a
= 1 – (3/5)2
= 1 – 9/25
= 16/25
Sin a = sqrt(16/25)
= 4/5
Q.2: If cos x = 5/13, then find sin2x and sin x.
Solution:
Given,
cos x = 5/13
sin2x = 1 – cos2x
= 1 – (5/13)2
= 1 – 25/169
= 144/169
Therefore, sin x = 12/13
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