Question

Prove that sin(x+pi)=-sinx

Answer 1

you can use this formula :
sin(a + b) = sin(a)cos(b) + cos(a)sin(b)

in this case a = x and b = pi

Answer 2

My teacher got sinx(-1)+cosx(0). How did he get that from that formula?

Answer 3

sin(a + b) = sin(a)cos(b) + cos(a)sin(b)

change a = x and b = pi
sin(x + pi) = sin(x)cos(pi) + cos(x)sin(pi)

do you know the value of cos(pi) and sin(pi) respectively are ...