Help me Given conditions A+B+C=180°

then prove that:

sin(B+2C)+sin(C+2A)+sin(A+2B)=4si n{B-C/2}sin{C-A/2}sin{A-B/2}​

1. a parachutist is 800 feet above the ground when she opens her parachute. she then falls at a constant rate of 5 feet per second. select the equation that represents this situation. h = -800t + 5 y = -5x + 800 h = 5t - 800 y = 800x + 5 i need

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

D(5, 7). e(4,3), and f(8, 2) form the vertices of a triangle. what is mzdef? oa. 30° ob. 45° oc. 60° od 90°