180< x < 270 so x is in 3rd quadrant ,hence tan x is positive cos x=-4/5 tan(x/2) = √ {(1 − cos x) / (1 + cos x)) = √ { (1+4/5)/(1–4/5) } =√{ 9/5)/(1/5) } =√9=±3 now ...
Exponent is the expression in where you convert product factor expression into a shorter expression. So really you use it to make the question simpler and shorter(easier to understand).
Multiples of 15 are: 15,30,45,60,75,90,105,120,135,150,165,180,195,210,225,240,255,270,285,300,315,330,345,360,375,390,405,420,435,450,465,480,495,510,525,540,555,570,585,600,615,630,645,660,675,690,705,720,735,
