Definite Integral/Examples/Cosine of x from 0 to pi by 2

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Example of Definite Integral

$\ds \int_0^{\pi / 2} \cos x \rd x = 1$


Proof

\(\ds \int_0^{\pi / 2} \cos x \rd x\) \(=\) \(\ds \bigintlimits {\sin x} 0 {\pi / 2}\) Primitive of Cosine Function
\(\ds \) \(=\) \(\ds \sin \dfrac \pi 2 - \sin 0\) Definition of Definite Integral
\(\ds \) \(=\) \(\ds 1 - 0\) Sine of Right Angle, Sine of $0 \degrees$
\(\ds \) \(=\) \(\ds 1\)

$\blacksquare$


Sources