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प्रश्न
If sin 3A = 1 and 0 < A < 90°, find cos 2A
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उत्तर
sin 3A = 1
sin 3A = sin90°
3A = 90°
A = 30°
cos 2A = cos 2(30°)
= cos 60°
= `(1)/(2)`
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