Q. Prove the following: 1+3cos(theta)-4cos^3(theta)/1-cos(theta) = (1+2cos(theta))^2

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Q. f(4x+5)=12x+18 , find the f'(x) Soln: Let 4x + 5 = a or, x = (a-5)/4 Then, f(a) = 12*(a - 5)/4 + 18 = 3*(a - 5) ...
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Q. 8cos^3(20) - 8sin^3(10) - 6cos20 + 6sin10 = 2 Soln: L.H.S. = 8cos320 – 8sin310 – 6cos20 + 6sin10 = 2(4cos320 – 4sinn310 – 3cos20 + 3sin10) = 2(4cos320 - 3cos20 + 3sin10 ...
Q. Evaluate: Cos6° × sin24° × cos72° Soln: Cos6° × sin24° × cos72° = (1/2) * 2 Cos6° × sin24° × cos72° = (1/2) [sin(6+24) – sin(6-24)] * cos72 = (1/2) ...