Answer:
40 squared cm
Explanation:
The formula for this shape would be
A=bh
This is the same as a rectangle because it is technically a rectangle, don't get confused by the triangle.
Imagine that you can cut this shape, so cut where the dotted line is, put it on the opposite side, and you get a rectangle.
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So:
10 × 4 = 40
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Have a good day :)