Question 1201668
1/cos^2(x) + 1/sin^2(x) is the original expression.
multiply 1/cos^2(x) by sin^2(x)/sin^2(x) and multiply 1/sin^2(x) by cos^2(x)/cos^2(x).
you will get:
sin^2(x)/(sin^2(x)cos^2(x)) + cos^2(x)/(sin^2(x)cos^2(x))
that becomes (sin^2(x) + cos^2(x))/(sin^2(x)cos^2(x))
which becomes 1/(sin^2(x)cos^2(x)) because sin^2(x) + cos^2(x) = 1.