2. In the range of 0 to 2π, the angle 2π/3 is the same as the terminal edge of the angle -4π/3.
∵-4π/3+2π=2π/3
3. if cos α >; 0,sinα& lt; 0, and the terminal edge of angle α is in the fourth quadrant.
cosα& gt; 0 = = >; α lies in 1, 4 (positive direction of X axis)
sinα& lt; 0 = = >; α is in 3,4 (negative Y axis)
Male Quadrant 4 * * *
4.√( 1-sin? 440 )=√cos? 440? =|cos440? |=|cos(360? +80? )|=cos80?
5. Simplify SIN (180+2α)/1+cos2α× [cos2α/cos (90+α)].
=sin2α/(2cos? α) ×cos? α/(-sinα)= 2 sinαcosα/[2(-sinα)]=-cosα
D.- Kossa