Answer:
10 in
Explanation:
There are two ways to work this problem, and they give different answers. The reason for that is that the data shown in the diagram is not consistent.
Method 1
Use the area to determine the base length. The area formula is ...
A = (1/2)bh
20 in^2 = (1/2)(b)(4 in)
(20 in^2)/(2 in) = b = 10 in
The missing side dimension is 10 inches.
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Method 2
Use the Pythagorean theorem to find the parts of the base, then add them up.
Left of the "?" we have ...
left^2 +4^ = 6^
left^2 = 36 -16 = 20
left = √20 = 2√5
Right of the "?" we have ...
right^2 +4^2 = 8^2
right^2 = 64 -16 = 48
right = √48 = 4√3
So, the base length is ...
base = left + right = 2√5 +4√3
base ≈ 11.400 in
The missing side dimension is 11.4 inches. (The area is 22.8 in^2.)