+0

trig

0
75
1

Simplify $$\left( \dfrac1{\cos a} - \dfrac{\sin a}{\cos a} \right) \left( \dfrac1{\cos a} + \dfrac{\sin a}{\cos a} \right)$$

Jun 24, 2020

#1
+2306
+1

I think this will be the same as this rule:

(a+b)(a-b)=a^2-b^2