Question

what is the surface area of this triangular prism?
12 mm
15 mm
30 mm
9 mm
square millimeters

Explanation:

Step1: Find base triangle area

The triangular base is a right triangle, so area is $\frac{1}{2} \times 9 \times 12 = 54$ mm². Two such bases: $2 \times 54 = 108$ mm².

Step2: Calculate area of 3 rectangles

• Rectangle 1: $9 \times 30 = 270$ mm²
• Rectangle 2: $12 \times 30 = 360$ mm²
• Rectangle 3: $15 \times 30 = 450$ mm²

Sum of rectangles: $270 + 360 + 450 = 1080$ mm².

Step3: Total surface area

Add base areas and rectangle areas: $108 + 1080 = 1188$ mm².

Answer:

1188