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Zorluk: OrtaDefinite Integrals and Area Under Curves

What is the value of the definite integral ∫0π2(3sin⁡x+2cos⁡x) dx\int_{0}^{\frac{\pi}{2}} (3\sin x + 2\cos x) \, dx?

  1. 55Cevap
  2. B
    22
  3. C
    −1-1
  4. D
    −5-5

Cevap

The value of the definite integral is 55.
The antiderivative of 3sin⁡x+2cos⁡x3\sin x + 2\cos x is −3cos⁡x+2sin⁡x-3\cos x + 2\sin x. Evaluating this expression at the upper limit x=π2x = \frac{\pi}{2} gives 22, and at the lower limit x=0x = 0 gives −3-3. Applying the Fundamental Theorem of Calculus gives 2−(−3)=52 - (-3) = 5.

Adım Adım Çözüm

1
Find the indefinite integral of 3sin⁡x+2cos⁡x3\sin x + 2\cos x
∫(3sin⁡x+2cos⁡x) dx=−3cos⁡x+2sin⁡x\int (3\sin x + 2\cos x) \, dx = -3\cos x + 2\sin x
The antiderivative of sin⁡x\sin x is −cos⁡x-\cos x and the antiderivative of cos⁡x\cos x is sin⁡x\sin x.
2
Evaluate the antiderivative at the upper limit x=π2x = \frac{\pi}{2}
-3\cos\left(\frac{\pi}{2}\right) + 2\sin\left(\frac{\pi}{2}\right) = -3(0) + 2(1) = 2
Substitute x=π2x = \frac{\pi}{2} into the antiderivative expression.
3
Evaluate the antiderivative at the lower limit x=0x = 0
-3\cos(0) + 2\sin(0) = -3(1) + 2(0) = -3
Substitute x=0x = 0 into the antiderivative expression.
4
Subtract the lower limit value from the upper limit value
2 - (-3) = 2 + 3 = 5
By the Fundamental Theorem of Calculus, ∫abf(x) dx=F(b)−F(a)\int_{a}^{b} f(x)\,dx = F(b) - F(a).

Anahtar Kavram

Definite Integration of Trigonometric Functions
Tahmini Süre:1m 30s
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