Double-angle formulae
Trigonometric ratios and identities · Mathematics
Study notes
Q: If sin A = 3/5 (acute), find sin 2A and cos 2A. cos A = 4/5. sin 2A = 2(3/5)(4/5) = 24/25. cos 2A = 1 - 2(9/25) = 7/25.
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Trigonometric ratios and identities · Mathematics
Q: If sin A = 3/5 (acute), find sin 2A and cos 2A. cos A = 4/5. sin 2A = 2(3/5)(4/5) = 24/25. cos 2A = 1 - 2(9/25) = 7/25.