Exercise · ZW-FUBINIS-THEOREM-005 · ★☆☆ Basic
Compute \(\iint_R \sin x\cos y\,dA\) over \(R=[0,\tfrac{\pi}{2}]\times[0,\tfrac{\pi}{2}]\).
Choose one option.
Show answer
- B. \(1\)
Explanation
\(\int_0^{\pi/2}\sin x\,dx=1\) and \(\int_0^{\pi/2}\cos y\,dy=1\), so the integral equals \(1\).
Review the concept: Fubini's theorem
If \(f\) is continuous on a rectangle \(R=[a,b]\times[c,d]\), its double integral with respect to the area \(A\) is computed as an iterated integral, integrating in either order.
\[\iint_R f\,dA=\int_a^b\!\int_c^d f(x,y)\,dy\,dx=\int_c^d\!\int_a^b f(x,y)\,dx\,dy\]
More practice problems: fubini's theorem
- ZW-FUBINIS-THEOREM-001 Compute iint_R xy dA over R=[0,2]×[0,3].
- ZW-FUBINIS-THEOREM-002 Compute iint_R (x+y) dA over R=[0,1]×[0,2].
- ZW-FUBINIS-THEOREM-003 Compute iint_R e^x+y dA over R=[0,1]×[0,1].
- ZW-FUBINIS-THEOREM-004 Compute iint_R x^2y dA over R=[1,2]×[0,1].
- ZW-FUBINIS-THEOREM-006 Compute iint_R 6xy^2 dA over R=[0,1]×[-1,1].
- ZW-FUBINIS-THEOREM-007 Let f be continuous on R=[a,b]×[c,d]. What does Fubini's theorem state?
- ZW-FUBINIS-THEOREM-008 Compute iint_R xe^xy dA over R=[0,1]×[0,1]. It helps to integrate in y first.
- ZW-FUBINIS-THEOREM-009 If f(x,y)=g(x)h(y) with g,h continuous, what is iint_R f dA over R=[a,b]×[c,d]?