I need help with geometry please :)

If a and b are the measures of two first quadrant angles and sin a = 4/9 and sin b = 2/5 find sin(a+b).

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.1. (round your answers to four decimal places.) (a) if the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51?

Choose the domain & range of the relation shown in the graph: domain: -1, 0, 1, 2, 3 range: -3, -1, 0, 3 domain: -3, -1, 0, 3 range: -3, -1, 0, 3 domain: -3, -1, 0, 3 range: -1, 0, 1, 2, 3 domain: 3, 1, 0, 3 range: -1, 0, 1, 2, 3