make a diagram showing a right angled triangle with hypotenuse of 8
let the base be x and the height be y
given : dx/dt = 1
find: dy/dt when x=5
a) when x=5 , 2+ y^2 = 64
y = √39
x^2 + y^2 = 64
2x dx/dt + 2y dy/dt = 0
dy/dt = -x dx/dt/y
= -5(1)/√39 = - .8 ft/sec
(the negative value of dy/dt shows y is getting smaller)
b) follow the same steps as above
an 8ft 2 by 4 is leaning against a 10ft wall. THe lower end of the 2 by 4 is pulled away from the wall at the rate of 1ft/sec. How fast is the top of the 2 by 4 moving toward the ground (a) when it is 5 ft from the ground and (b) when it is 4 ft from the ground?
1 answer
1 answer