Mathematics

Solve :
$$\int cos^3x . dx$$


SOLUTION
$$\displaystyle \int cos^{3}xdx $$
we know that 
$$\displaystyle cos^{3}x = 4cos^{3}x-3cosx $$
$$ \dfrac{cos3x+3cosx}{4} = cos^{3}x $$
put the value of $$ cos^{3}x $$
$$\displaystyle = \int \frac{cos3x+3cox}{4}dx $$
$$ \displaystyle = \frac{1}{4}\int (cos3x+3cosx)dx $$
$$\displaystyle = \frac{1}{4}[\frac{sin3x}{3}+3sinx]+c $$ 
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Subjective Medium Published on 17th 09, 2020
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