Tích phân $\Large \int\limits_{\pi}^{\frac{\pi}{2}}\cos x\text{d}x$ bằ

Tích phân $\Large \int\limits_{\pi}^{\frac{\pi}{2}}\cos x\text{d}x$ bằng

• A. $\Large 1$.
• B. $\Large \dfrac{\pi}{2}$.
• C. $\Large \dfrac{1}{2}$.
• D. $\Large -1$.

Chọn A

Ta có $\Large \int\limits_{\pi}^{\frac{\pi}{2}}\cos x\text{d}x=\sin x\Big|_{\pi}^{\frac{\pi}{2}}=\sin\left(\dfrac{\pi}{2}\right)-\sin \pi=1$.