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Please Solve RD Sharma Class 12 Chapter 19 Definite Integrals Exercise 19.3 Question 15 Maths Textbook Solution.

Answers (1)

Answer:  4

Hint: We will use the concept of even function to solve the integral.

Given:

                \int_{\frac{-\pi}{2}}^{\frac{\pi}{2}}\{\sin |x|+\cos |x|\} d x

Solution:

\begin{aligned} &I=\int_{\frac{-\pi}{2}}^{\frac{\pi}{2}}\{\sin |x|+\cos |x|\} d x \\ & \end{aligned}

f(-x)=\sin |-x|+\cos |-x|=\sin |x|+\cos |x|=f(x)

                 

\begin{aligned} &f(x) \text { is a even function }\\ & \end{aligned}

I=2 \int_{0}^{\frac{\pi}{2}}(\sin x+\cos x) d x

\begin{aligned} &{\left[\text { for even function } \int_{\frac{-\pi}{2}}^{\frac{\pi}{2}} x d x=2 \int_{0}^{\frac{\pi}{2}} x d x\right]} \\ & \end{aligned}

I=2[-\cos x+\sin x]_{0}^{\frac{\pi}{2}} \\

I=2[(0+1)-(-1-0)] \\

I=2(2)=4

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