a) let A(2mt^2, 2mt) and B(2ms^2,2ms) be two points on C, find the slope of the tangent to C at A and the slope of AB in terms of s and t.
b) if the line AB is perpendicular to the tangent to C at A, express L^2 in terms of m and t, where L is the length of AB.
c) suppose m<0. Find the value of t such that L attains its minimum value, Hence, find the minimum value of L in terms of m.
part b and c thanks!!
The volume of a right circular cone is 128 pi/3 cm^3. Let h cm and r cm be the vertical height and the base radius of the cone respectively.
a) Express r^2 in terms of h
b) Show that the slant height of the cone is given by sqrt(h^2 +128/h) cm.
c) Find the minimum slant height.
part c thanks!!
更新1:
please help >
更新2:
thank you so much for answering me! but can you explain why the value of t is only -sqrt(2)/2? and why is the minimum L^2 = m^2 (1+2)^3?
更新3:
i understand why the minimum is L^2 = m^2 (1+2)^3 now. but i still don't know why the value of t is only -sqrt(2)/2
更新4:
but the answer given by my textbook is - sqrt(2)/2, is it wrong?
