`Delta=|(cos""(theta)/(2),1,1),(1,cos""(theta)/(2),-cos""(theta)/(2)),(-cos""(theta)/(2),1,1)|` lies in the interval

If theta, phi epsilon R , then the determinant Delta=|(cos theta, - sin theta, 1),(sin theta, cos theta, 1),(cos(theta+phi),-sin(theta+phi),0)| lies in the interval

1+cos theta=2cos^(2)theta

(tan^(2)theta)/((sec theta-1)^(2))=(1+cos theta)/(1-cos theta)

(sin^(8)theta-cos^(8)theta)/(cos2theta(1+cos^(2)2theta))=?

For -(pi)/(2)

(1)/(1-cos theta)-(1)/(1+cos theta)=(2cos theta)/(sin^(2)theta)=2cot theta xx csc

prove that (cos theta)/(1-sin theta)+(cos theta)/(1+sin theta)=(2)/(cos theta)

Prove (cos ec theta-cot theta)^(2)=(1-cos theta)/(1+cos theta)

root(7)((1+cos theta)/(1-cos theta))+sqrt((1-cos theta)/(1+cos theta))=2cos ec theta