text: if sin a+cosec a=2.find the value of sin^2a+cosec^2.?   (sin a + cosec a)^2 = 4 sin^2 a + 2sinacoseca + cosec^2 a = 4  cosec a = 1/sina which means that sinacoseca = 1 and 2sinacoseca = 2  therefore sin^2 a + 2 + cosec^2 a = 4 sin^2 a + cosec^2 a = 4-2 = 2  (im guessing that the "cosec^2" in your qn is supposed to be "cosec^2 a).