1) tg(-π/4) sin(-37π/6)

tg(-π/4) = -1

sin(-37π/6) = sin(-6π - π/6) = sin(-π/6) = -sin(π/6) = -1/2

Therefore, tg(-π/4) sin(-37π/6) = -1 * -1/2 = 1/2

2) Given: cos 90 degrees

cos 90 degrees = 0

Therefore, the value of cos 90 degrees is 0.