Evaluate : `int(cosx)/(("cos"(x)/(2)+"sin"(x)/(2))^(3))dx`.

1.	Evaluate : `int(cosx)/(("cos"(x)/(2)+"sin"(x)/(2))^(3))dx`.
Answer» `int(cosx)/(("cos"(x)/(2)+"sin"(x)/(2))^(3))dx=int(cos^(2)(x//2)-sin^(2)(x//2))/({cos(x//2)+sin(x//2)}^(3))dx` `=int(cos(x//2)-sin(x//2))/(("cos"(x)/(2)+"sin"(x)/(2))^(2))dx=2int(1)/(t^(2))dt," where t=cos"(x)/(2)+"sin"(x)/(2)` `=(-2)/(t)+C=(-2)/(cos(x//2)+sin(x//2))+C`

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