Answer:
the answer is D: 294 sq. cm
Explanation:
first you want to split the net into 4 triangles and 1 rectangle
a = 12 cm
b = 6 cm
d = 13 cm
calculate the surface area of the pyramid...
1st find the area of the rectangle base
Rectangle base area
b x a = (6 cm) (12 cm)
= 72 sq. cm
next find the area of the triangle on the left
Left triangle
1/2(b)(d) = 1/2 (6 cm)(13 cm)
= 1/2 (78 sq cm)
= 39 sq. cm
Since all the triangles are congruent (same), you will need to multiply by 2 to get the combined area of the triangle on the left and on the right.
Area of left & right triangles
= 2 (39 sq. cm)
= 78 sq. cm
Find the area of the triangle on the bottom
Bottom triangle area = 1/2 (a)(a)
= 1/2 (12 cm) (12 cm)
= 1/2 (144 sq. cm)
= 72 sq. cm
Since the bottom of the triangle is congruent to the top triangle, multiply that by 2 to get a combined area of the triangle on the bottom and top
Area of top & bottom triangles
2 (72 sq. cm) = 144 sq. cm
Finally...add the area of the 4 triangles to the area of the rectangular base
72 + 78 + 144 = 294 sq. cm