Please help it’s due soon and I’ll give you a lot of points for it so please give me the full answer thanks

Aregular polygon has angkes of size 150° each.how many side has the polygon

At what time will the interfering waves have an amplitudeof zero?

Atank has a shape of a cone with a radius at the top of 2 m and a height of 5 m. the tank also has a 1 m spout at the top of the tank. the tank is filled with water up to a height of 2 m. find the work needed to pump all the water out the top of the spout. (use 9.8 m/s2 for g and the fact that the density of water is 1000 kg/m3.)