12x1
12x2
12x3
12x4
12x5
12x6
12x7
12x8
12x9
12x10
Sec^2 x - 1 = tan^2x
Proof:
Sec^2x = 1+ tan^2x
1/cos^2x = 1 + sin^2x/cos^2x
<span>1/cos^2x - sin^2x/cos^2x = 1
</span>Using common denominator:
(1-sin^2x)/cos^2x = 1
sin^2x + cos^2 x = 1
cos^2 x = 1 - sin^2x
Substituting :
cos^2x/<span>cos^2x = 1
</span>1 = 1
Left hand side = right hand side
Ali has 13 CD's
Here's how I got my answer:
Step 1: Simplify
to 50. Which leaves us with 
Step 2: Simplify
to 5. Which leaves us with
.
Step 3: Simplify
, to get your answer, 13.