Determine:
π2/4
∫ [((cos.sqrt(x))/ sqrt (x) ] dx
0
π2/4
∫ [((cos.sqrt(x))/ sqrt (x) ] dx
0
-
∫cos(√x))/√x dx from 0 to π²/4
u = √x
2 du = dx/√x
2*∫cos(u) du eval. from 0 to π/2
2*sin(u) eval. from 0 to π/2
= 2
u = √x
2 du = dx/√x
2*∫cos(u) du eval. from 0 to π/2
2*sin(u) eval. from 0 to π/2
= 2
-
u substitution
u = sqrt(x)
du = dx / (2 * sqrt(x))
Now we have:
2 * cos(u) * du
Integrate
2 * sin(u) + C
Back-substitute
2 * sin(sqrt(x)) + C
From 0 to pi^2 / 4
2 * sin(sqrt(pi^2 / 4)) - 2 * sin(sqrt(0)) =>
2 * sin(pi/2) - 2 * sin(0) =>
2 * 1 - 2 * 0 =>
2 - 0 =>
2
u = sqrt(x)
du = dx / (2 * sqrt(x))
Now we have:
2 * cos(u) * du
Integrate
2 * sin(u) + C
Back-substitute
2 * sin(sqrt(x)) + C
From 0 to pi^2 / 4
2 * sin(sqrt(pi^2 / 4)) - 2 * sin(sqrt(0)) =>
2 * sin(pi/2) - 2 * sin(0) =>
2 * 1 - 2 * 0 =>
2 - 0 =>
2