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Question
If A = 30o, then prove that :
2 cos2 A - 1 = 1 - 2 sin2A
Solution
Given A = 30°
2 cos2 A – 1 = 2 cos2 30° – 1
=`2(3/4) – 1`
= `(3)/(2) – 1`
= `(1)/(2)`
1 - 2 sin2A = 1 - 2 sin2 30°
= 1 - 2`(1/4)`
= `1/2`
∴ 2 cos2A – 1 = 1 – 2 sin2A
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