Help me please I don’t understand this question

The radius of the circle is 4 cm and the measure of the central angle is 90° the area of the sector with a central angle measuring 90° and radius of length 4 cm is vt cm the triangle in the sector is 4 cm the area of the triangle is v/cm² the area of the segment of the circle is (471 - ) cm?

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).

Using elimination, what is -4x+2y=-12 4x+8y=-24