- prove that sec^2thia = cos^2thita can never be less than 2
- xcothita-ysinthita=a xsinthita+ycosthita=b then prove that x^2+y^2=a^2+b^2
- prove that sec^2thia = cos^2thita can never be less than 2
- xcothita-ysinthita=a xsinthita+ycosthita=b then prove that x^2+y^2=a^2+b^2










