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J.L.
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
Are you familiar with the concept that similar figures have a ratio for area?
I mean as in if there is a ratio between side lengths a : b, then the ratio fo the areas is \(a^2 : b^2\)
im thinking area of big triangle - area of small triangle = area of trapezoid
Yea I know what you're talking about @Calcmathlete
Yup. First you have to find the area of the smaller triangle though. If a : b is 2 : 5, then what is \(a^2 : b^2\)?
how did you get 2:5 again?
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.
Why do you say it should be 4 : 5?
Because that's the ratio of the corresponding sides...CB=4 and BE=5 so the ratio would be 4:5 or 0.8
Are we looking at the same picture?
Sorry I was looking at a different question haha
shouldn't it be 4:6 then or 2:3?
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.
Ok. Now subtract the areas of the two triangles.
I know the area of the first triangle is 50...what's the area of the second?
Area of the second triangle = 8
lol Thanks @lgbasallote Clearly you need to brush up on those geometry skills ;)
hmm it always is 42 huh