The option 4 is correct.
Further explanation:
The given figure is the composite figure that involves some two dimensional shapes.
It can be better understand through the attached figure.
Option 1: Three triangles and a circle
It can be seen that in the given figure there is not any three triangles.
Therefore, option 1 is not correct.
Option 2: Two triangles, a rectangle and a circle.
It can be seen that in the given figure there is not any two triangles and a circle.
Therefore, option 2 is not correct.
Option 3: a triangle, a pentagon and a semicircle
It can be seen that in the given figure there is not any pentagon.
Therefore, option 3 is not correct.
Option 4: a triangle, a rectangle and a semicircle
It can be seen from the attached figure that there is one rectangle, one triangle, one semicircle.
The area of the combined figure is the sum of area 1, area 2, area 3 and area 4.
Area 1 represents the triangle, area 2 represents the rectangle, area 3 represents semicircle.
Therefore, option 4 is correct.
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Answer details:
Grade: Middle school
Subject: Mathematics
Chapter: Two dimensional figure
Keywords: triangle, rectangle, area, semicircle, pentagon, circle, figure, composite figure, combined figure, sum, decomposition, shapes