What is the measure of the exterior angle?

Which expression gives you the distance between the points (5,1)and(9,-6)

Marquise has 200 meters of fencing to build a rectangular garden. the garden's area (in square meters) as a function of the garden's width w w (in meters) is modeled by: a ( w ) = − w 2 + 1 0 0 w a(w)=−w 2 +100w what side width will produce the maximum garden area? meters

The measurement of one angle of a right triangle is 42° what is the measurement of the third angle? (there is no picture)