Find the exact value of the trigonometric expression given cos (22.5 ).

Use the identity   cos^2 (a/2) =  1/2 (1 + cos a) so

cos^ 2 22.5  = cos^2 (45/2)  = 1/2 ( 1 + cos 45)  =  1/2(1 + sqrt2/ 2)4 = 1/2 + sqrt2/4

cos 22.5  =  sqrt ( 1/2 + sqrt2/4)  Answer

Answercounterclockwise rotation about the origin by 180 degrees followed by reflection about the y-axisexplanationthe given figure has verticesrecall that for counterclockwise rotation about the origin, when we rotate figure pqrs counterclockwise through an angle of 180° about the origin, the coordinates will becomenext, we reflect in the y-axis by negating the x-coordinates of the resulting figure to obtain,therefore the correct answer is c