Can someone explain this to me and tell me the answer please?

Evaluate cos2θ for cosθ = square root of 3/2

(mc 02.03) what set of reflections and rotations would carry rectangle abcd onto itself? reflect over the y-axis, reflect over the x-axis, rotate 180° rotate 180°, reflect over the x-axis, reflect over the line y=x reflect over the x-axis, rotate 180°, reflect over the x-axis rotate 180, reflect over the y-axis, reflect over the line y=x

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?