Question 428019
Solution:As we know {{{sec(theta)=1/cos(theta)}}} and 

{{{csc(theta)=1/sin(theta)}}} We rewrite our trigonometric identity:

{{{(1/sec(theta))^2+(1/csc(theta))^2}}}=

{{{(cos(theta))^2 +(sin(theta))^2=1}}}

Done.