Given that tany= x^2tany=x2, what is the value of dy/dxdydx?

1 Answer
Dec 7, 2016

dy/dx = (2x)/sec^2ydydx=2xsec2y

Explanation:

We write tanytany as siny/cosysinycosy and differentiate using the quotient rule (with respect to xx) .

siny/cosy = x^2sinycosy=x2

(cosy(cosy)(dy/dx) - (-siny xx siny)dy/dx)/(cosy)^2 = 2xcosy(cosy)(dydx)(siny×siny)dydx(cosy)2=2x

(cos^2y(dy/dx) + sin^2y(dy/dx))/cos^2y = 2xcos2y(dydx)+sin2y(dydx)cos2y=2x

We use the identity sin^2beta + cos^2beta = 1sin2β+cos2β=1 to simplify further...

(dy/dx)/(cos^2y) = 2xdydxcos2y=2x

Use the identity sectheta = 1/costhetasecθ=1cosθ...

dy/dxsec^2y = 2xdydxsec2y=2x

dy/dx = (2x)/sec^2ydydx=2xsec2y

Hopefully this helps!