q. sin x cos x if (a) tan2x = ? (c) tan2x = a 1 — , is equal to cos x 27 cos x 27 125 125 sin (b)...
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DPP - 11
Trigonometry
1. Prove that : cos4A - sin4 A + 1 = 2 cos2 A.
2. Prove that : (sin A + cos A) (1 - sin A cos A) = sin3 A + cos2A.
3. Prove that : cosec A. sinA 1+cosA
+ = 21+cosA sin
4. Prove that : 2cosecA cosecA
+ = 2sec A.cosecA-1 cosecA +1
secA- tanA
secA +tanA5. Prove that : 1 - 2 sec A tan A + 2 tan2A .
6. Prove that : cotA+tanB
= cot A tan B.cotB+tanA
7. Prove that : 1 1 1 1
- = -cosecA-cotA sinA sinA cosecA +cotA
8. Prove that : . tanA+secA-1 1+sinA
=tanA-secA+1 cosA
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