5 (0<x<180). Tính các giá trị :
a) cot (180-x) .sin (90-x)
b) tan (180-x) .sin (90-x)
c) 2cot (90-x) .tan(180-x)
d) 2tan (90-x) .sin(180-x)

Cho sin x=3/5 (0Cho sin x=3/5 (0<x<180). Tính các giá trị :a) cot (180-x) .sin (90-x)b) tan (180-x) .sin (90-x)c) 2cot (90-x) .tan(180-x)d) 2tan (90-x) .sin(180-x)