When a pendulum swings 35degree from the vertically, the weight moves 15cm horizontally and 5.3 vertically. The length of the pendulum____?
draw the figure.
if L is the length, then the angle moved is theta, where sinTheta=15/L
and, cosTheta=(L-5.3)/L
but sin^2 + cos^2=1
225/L^2 + (L-5.3)^2/L^2=1
225 + L^2 -10.6L+5.3^2=L^2
-10.6L=-225-5.3^2
solve for L
check my work