Hey there! I'm happy to help!
The surface area is just the area of this net. If you fold up the net it will give you a hollow 3-d shape.
On this net we have three congruent rectangles and two congruent triangles.
We see that each rectangle has a short side of 10 cm and a long side of 15 cm. The area of a rectangle is found by multiplying the long side by the short side.
15×10=150
So, each rectangle has an area of 150 cm².
Now, for the triangles. To find the area of a triangle you multiply the base by the height and then divide by two.
Each triangle has a base of 10 cm and a height 8 2/3 cm.
We multiply them.
10×8 2/3=86 2/3
And we divide by two.
86 2/3 ÷ 2 = 43 1/3
So, each triangle has an area of 43 1/3.
Now, we add together the areas of our three rectangles and two triangles.
150+150+150+43 1/3+43 1/3=536 2/3
Therefore, the surface area is 536 2/3 cm².
Have a wonderful day!
