Step-by-step explanation:
just think a little bit.
congruent rectangles means they are all of equal size.
so, the sizes of all of these rectangles are 3×4.
therefore, the area of each one is 3×4 = 12 cm².
the total surface area (without the top
and bottom stars) is the sum of the areas of all rectangles.
how many rectangles are there ?
well, every "arm" of the star has 2 rectangle sides. and there are 5 "arms". so, there are 2×5 = 10 rectangles.
now it is really easy, right ?
we have 10 rectangles, each one with an area of 12 cm².
so the total surface area (without the star bases) is
12×10 = 120 cm²
