Evaluating Definite Integrals by Finding Antiderivatives
General
Grade 12
Question:
If $f(x) = \begin{cases} x, & x < 1 \\ \sin x, & x \geq 1 \end{cases}$, find $$\int_{0}^{\pi} f(x) dx$$
Step-by-Step Solution
Key Concept: General
Solution:<br>$$\int_{0}^{1} f(x) dx + \int_{1}^{\pi} f(x) dx$$<br>$$\int_{0}^{1} x dx + \int_{1}^{\pi} \sin x dx$$<br>$$= (x)_0^1 + (-\cos x)_1^{\pi} = 2 + \cos 1$$
Correct Answer: 2 + \cos 1