# ACT Math 5.1 Pre-Algebra

ACT Math: Pre-Algebra Drill 5, Problem 1. Factoring in depreciation, how much is the car worth?

 ACT Math Pre-Algebra ACT Mathematics Pre-Algebra Foreign Language Arabic SubtitledChinese SubtitledKorean SubtitledSpanish Subtitled Language English Language Pre-Algebra Data collection, representation, and interpretationPercentages Product Type ACT Math Ratios, Percentages, and Proportions Percents

### Transcript

00:23

To get rid of it, we multiply by one over sin squared alpha

00:28

The sines squared alpha cancels out on the top and bottom like this

00:31

which leaves us with one over cosine squared alpha -1

00:36

cosine and secant are inverse functions

00:39

so 1 over cosine squared alpha is the same thing

00:43

as secant squared alpha and the handy dandy trig identity

00:46

1 plus tangent squared alpha equals secant squared alpha

00:49

can be rearranged to become secant squared alpha -1

00:53

equals tangent squared alpha. What do you know? We're left with secant squared alpha

00:57

-1 in our expression

00:59

and we just figured out secant squared alpha -1 equals tangent squared alpha.

01:04

Which is option E.