Question

An envelope opens to form 1 rectangle and 4 triangles. Find the area of 4 such envelopes.

• A. 100 square inches
• B. 200 square inches
• C. 300 square inches
• D. 400 square inches

Answer 1

The correct option is B 200 square inches

Area of the rectangle
= Length × Width
= $6\times 4$
= 24 square inches

Area of Triangle A = Area of Triangle C
$=\frac{1}{2}\times Base\times Height$
$=\frac{1}{2}\times 4\times 2$
$=4$ square inches

Area of Triangle B = Area of Triangle D
$=\frac{1}{2}\times 6\times 3=9$ square inches

Area of an envelope
= Area of the rectangle + Area of Triangle A + Area of Triangle B + Area of Triangle C + Area of Triangle D
= 24 + 4 + 4 + 9 + 9 = 50 square inches

Area of 4 envelopes
= $50\times 4$
= 200 square inches