A. 它所围图形的面积为$A=4\int_{\frac{\pi}{6}}^{\frac{\pi}{3}}a\sin^{3}t(-3\sin t\cdot\cos^{2}t)dt$.
B. 它的周长为$L=4\int_{\frac{\pi}{6}}^{\frac{\pi}{3}}3a\sin t\cdot\cos tdt$.
C. 它绕x轴旋转而成旋转体的体积为$V_{x}=3\pi a^{3}\int_{0}^{\frac{\pi}{2}}\sin^{7}t(1-\sin^{2}t)dt$.
D. 它绕x轴旋转而成旋转体的体积为$V_{x}=6\pi a^{3}\int_{0}^{\frac{\pi}{2}}\sin^{7}t(1-\sin^{2}t)dt$.
25.计算星形线 =a(cos )^3t =a(sin )^3t 图 6-26) 的全长.-|||-yì-|||-a-|||-x=acos^3-|||-asin
25.计算星形线 =a(cos )^3t, =a(sin )^3t 图 -26 的全长.
6.求由下列各曲线所围成的图形的面积：(1)ρ=2acosθ; (2)x=acos^3t,y=asin^3t; (3)ρ=2a(2+cosθ).6.求由下列
2.应用格林公式计算下列曲线所围的平面面积:-|||-(1)星形线: =a(cos )^3t, =a(sin )^3t;-|||-(2)双纽线: (({x)^2
[例18] 设f(x)连续,试求下列函数的导数.-|||-(1) (int )_({e)^x}f(t)dt;-|||-(2) (int )_(0)^x(x-t)
[例18]设f(x )连续,试求下列函数的导数.-|||-(1)f(t)dt;-|||-(2) (int )_(0)^x(x-t)f(t)dt ;-|||-(3
[单选题]设x，y，t均为int型变量，执行语句：x＝y=3；t=++x||++y；，完成后，y的值为( )。A．不确定B．4C．3D．1
[单选题]设x,y,t均为int型变量，执行语句：x=y=3;t=++x||++y;完成后，y的值为A．不确定B．4C．3D．1
1.求下列曲线的弧长:-|||-(1) =(x)^3/2, (2)、 sqrt (x)+sqrt (y)=1;-|||-(3) =a(cos )^3t, =a(
=Asin omega (t+1)-|||-C =Acos omega t(t+1)-|||-D. =Acos omega (t-1)