Step-by-step explanation:
the area of a triangle is
baseline × height / 2
we have here 2 triangles : the larger, outer shaded one, and the smaller, inner white one.
to get the area of the shaded part, we need to calculate the area of the large triangle and subtract the area of the smaller triangle.
large area :
12 × 15 / 2 = 6 × 15 = 90 ft²
small area :
8 × 10 / 2 = 4 × 10 = 40 ft²
the shaded area is
90 - 40 = 50 ft²
It would be equal to 110 2/7
Answer:
Surface area = 2 (lw + lh + wh)
= 2 [(5*4) + (5*7) + (7*4)]
= 166 sq.mm
