Question

-2 cos (-300 degrees)

Answer 1

we can also write 300 degree is radians = 300 . pi/180
= 5.pi/3
now, cos ( 5pi/3) can also be written as.... cos( 2pi - pi/3)
which is also equals to.... cos(pi/3)
and cos(pi/3) = 1/2
also, cos(-theta) = cos(theta)
now, the given question , -2 cos(-300 deg.)
= -2 cos(300 deg.)
= -2. 1/2
= -1