Verify the identity cos^2x+csc^2x*cos^2x+sin^2x=csc^2x

Liz had 140 pens and inna had 100 pens. after inna gave liz some pens, liz had 3 times as many pens as inna. how many pens did inna give liz?

Prove sin2a + cos2a - 1 / sin2a + cos2a + 1 = 1 - tana / 1 + cota

Line wx is parallel to line yz. if m