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ACT Math Videos 161 videos
ACT Math: Plane Geometry Drill 3, Problem 1. What is the area of the trapezoid shape in the video?
ACT Math Pre-Algebra Drill 1, Problem 3. Can you find the product of two square roots?
ACT Math Intermediate Algebra Drill 2, Problem 2. How else can the expression be written?
ACT Math 5.1 Pre-Algebra 466 Views
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Description:
ACT Math: Pre-Algebra Drill 5, Problem 1. Factoring in depreciation, how much is the car worth?
Transcript
- 00:02
And here is your shmoop de jour.
- 00:04
Simplified tangents squared alpha over sine squared alpha minus 1
- 00:10
And here are the potential answers...
- 00:14
Okay well whenever we see a tangent we can change
- 00:18
to sine over cosine. Now we have a triple layer fraction cake.
Full 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.
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