ShmoopTube

Where Monty Python meets your 10th grade teacher.

Search Thousands of Shmoop Videos

ACT Math 3.1 Trigonometry 257 Views


Share It!


Description:

ACT Math: Trigonometry Drill 3, Problem 1. What is side DE?

Language:
English Language

Transcript

00:02

For a good time, solve this shmoopy question...

00:05

For the right triangle DEF, F = 60° and DF = 10.  What is DE?

00:12

And here are your potential answers...

00:15

OK this problem is really testing one thing and one thing only...

00:18

...whether we recognize that we have a 30-60-90 triangle here.

00:22

But if we do recognize it, then we know that this angle is 90 degrees... F here is 60 degrees...

00:29

and E here is 30 degrees.

00:31

We should know that the ratio of the sides of a 30-60-90 triangle is 1 to square root

00:35

of 3 to 2.

00:36

If we label each side we have 1 here, square root of 3 here and 2 here.

00:43

The question asks for the length of DE; well, we know that DE is to DF as square root of

00:49

3 is to 1...

00:51

DF has a length of 10 and

00:53

the key equation looks like this:

00:55

Square root of 3 over 1 equals DE over 10.

00:59

Cross multiply and we have 10 times square root of 3 equals 1 times DE... or just, uh, DE...

01:05

So the answer is B.

Up Next

ACT Math 3.1 Plane Geometry
2558 Views

ACT Math: Plane Geometry Drill 3, Problem 1. What is the area of the trapezoid shape in the video?

Related Videos

Inequalities in Number Lines
3224 Views

ACT Math: Coordinate Geometry Drill 1, Problem 1. Which inequality is expressed by the number line?

ACT Math 3.1 Intermediate Algebra
1954 Views

ACT Math: Intermediate Algebra: Drill 3, Problem 1. Find the fifth number in the series.

Surface Area of Cylinders
14740 Views

Haven't you always wondered how much cardboard it takes to encase a trunk warmer for your pet elephant?

Perimeter of Irregular Shapes
4864 Views

Want to figure out the area and perimeter of irregular shapes? Break them down into regular shapes. For example, a flower can be broken down into s...