Perimeter, Area, and Surface Area — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. Triangle with base 14 m and height 5 m has area 35 sq m.
A = 1/2 x 14 x 5 = 35 square meters using the triangle area formula.
2. An L-shape with parts 8x5 and 3x4 has total area 52 sq ft.
8 x 5 = 40 and 3 x 4 = 12, so total = 40 + 12 = 52 square feet.
3. Triangle with base 16 cm and height 6 cm has area 48 sq cm.
A = 1/2 x 16 x 6 = 48 square centimeters by the triangle formula.
4. A T-shape with 10x2 top and 4x6 stem has area 44 sq in.
10 x 2 = 20 and 4 x 6 = 24, so total area is 20 + 24 = 44 sq in.
5. A rectangle 9x4 with a 2x2 square attached has area 40 sq m.
9 x 4 = 36 and 2 x 2 = 4, so combined area is 36 + 4 = 40 square meters.
6. Triangle with base 20 ft and height 9 ft has area 90 sq ft.
1/2 x 20 x 9 = 90 square feet using the triangle area formula.
7. An L-shape with parts 6x6 and 4x3 has area 48 sq cm.
6 x 6 = 36 and 4 x 3 = 12, so total = 36 + 12 = 48 sq cm.
8. Triangle base 7 in, height 8 in has area 28 sq in.
A = 1/2 x 7 x 8 = 28 square inches for this triangle.
9. A 10x10 square joined with a 5x4 rectangle has total area 120 sq ft.
10 x 10 = 100 and 5 x 4 = 20, so combined area is 100 + 20 = 120 sq ft.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
L-shape
→ A = length x width
A = length x width
Triangle
→ Sum of decomposed parts
Sum of decomposed parts
Composite figure
→ Split into two rectangles, then add
Split into two rectangles, then add
Rectangle
→ A = 1/2 x base x height
A = 1/2 x base x height
L-shapes split into two rectangles, triangles use half base times height, composite figures sum decomposed parts, and rectangles use length times width.