You can solve this by using trigonometry and the formula SOH CAH TOA. You're looking for an angle that is adjacent (next to) 12, and opposite 18. Therefore, you will needed to use TOA, which stands for tangent = opposite/adjacent.
With substitution, this gives you tangent = 18/12. 18/12 is equal to 1.5. Because we are looking for an angle we need to use the tan^-1 (tan to the power of -1) button on our calculator. Tan(1.5)^-1 equals 56.31 to 2dp.
The kinetic energy of an object is given by: Kinetic energy = 1/2 * mass * velocity If the kinetic energy of the pendulum at the top of its swing is 0, then this tells us that the velocity of the pendulum at that point is 0
