Question

PLEASE HELP!

The figure below shows AB = 4 units and BD = 6 units.



If the area of triangle ADE is 50 square units, what is the area of the trapezoid BCED?

40 square units

44 square units

48 square units

42 square units
http://learn.flvs.net/webdav/assessment_images/educator_geometry_v14/pool_Geom_3641_Seg_Two_Exam_35/image0034e9d7dd7.jpg

Answer 1

Are you familiar with the concept that similar figures have a ratio for area?

Answer 2

de javu

Answer 3

Yea

Answer 4

I mean as in if there is a ratio between side lengths a : b, then the ratio fo the areas is \(a^2 : b^2\)

Answer 5

im thinking area of big triangle - area of small triangle = area of trapezoid

Answer 6

Yea I know what you're talking about @Calcmathlete

Answer 7

Yup. First you have to find the area of the smaller triangle though.
If a : b is 2 : 5, then what is \(a^2 : b^2\)?

Answer 8

4:25

Answer 9

how did you get 2:5 again?

Answer 10

Shouldn't it be 4:5?

Answer 11

The ratio of the similar triangles lgba.
Now, set up a proportion between the two areas.
\[\frac{4}{25} = \frac{x}{50}\]Solve for x.

Answer 12

Why do you say it should be 4 : 5?

Answer 13

Because that's the ratio of the corresponding sides...CB=4 and BE=5 so the ratio would be 4:5 or 0.8

Answer 14

Are we looking at the same picture?

Answer 15

Sorry I was looking at a different question haha

Answer 16

shouldn't it be 4:6 then or 2:3?

Answer 17

Not quite. That isn't the ratio of the triangles. Think about it. 6 is a part of the side of a triangle. Not the actual triangle.

Answer 18

Okay got it
x=8

Answer 19

Ok. Now subtract the areas of the two triangles.

Answer 20

I know the area of the first triangle is 50...what's the area of the second?

Answer 21

Area of the second triangle = 8

Answer 22

Ohhh
50-8=42

Answer 23

There you go :)

Answer 24

You are truly awesome

Answer 25

lol Thanks @lgbasallote Clearly you need to brush up on those geometry skills ;)

Answer 26

...clearly...

Answer 27

hmm it always is 42 huh