12 multiple-choice questions, progressively harder.
An orthogonal polygon is formed by removing an upper right rectangular corner 121212 cm wide and 999 cm deep from a 272727 cm by 161616 cm rectangle. Find its area and perimeter.
324 cm2324\text{ cm}^2324 cm2
128128128 cm
540 cm2540\text{ cm}^2540 cm2
868686 cm
444444 cm
Solution
Correct answer: C
The area loses the corner. Its two new orthogonal edges replace equal total horizontal and vertical lengths, leaving the perimeter unchanged.
A 202020 cm by 151515 cm rectangle contains a triangular hole strictly inside it. The hole has sides 101010 cm, 101010 cm, and 121212 cm. What is the total boundary length, including the hole?
Correct answer: A
Add the outer rectangle perimeter and all three sides of the hole.
Two polygonal regions have areas 969696 and 777777 square centimeters. Their common part has area 222222 square centimeters. What is the area of their union?
Correct answer: D
Adding counts the common part twice; subtract it once to count it once.
A 252525 cm by 171717 cm rectangle loses a 101010 cm by 777 cm rectangular corner. All remaining sides are horizontal or vertical. What is the perimeter of the remaining region?
Correct answer: B
Removing a corner replaces each lost horizontal or vertical length with an equal new one.
A 121212 cm by 777 cm rectangle and a right triangle with legs 121212 cm and 555 cm are joined along their full 121212 cm sides. Their interiors are disjoint. Find the union area and perimeter.
114 cm2114\text{ cm}^2114 cm2
144 cm2144\text{ cm}^2144 cm2
565656 cm
686868 cm
The triangle hypotenuse is 131313 cm by Pythagoras. Add the two areas; remove both copies of the common side from the perimeter sum.
A 292929 cm by 121212 cm rectangle has an upper right rectangular notch 666 cm wide and xxx cm deep. The retained area is 282282282 square centimeters. What is xxx?
The notch area is the outer area minus the retained area. Divide it by the notch width.
The depth is positive and below the full 121212 cm height.
Use 111 foot equal to 121212 inches. How many square inches is 2.252.252.25 square feet?
A one-foot square has twelve rows of twelve one-inch squares.
A rectangle measures 1.31.31.3 m by 757575 cm. A 202020 cm by 303030 cm rectangular hole lies strictly inside it. Use 111 m equal to 100100100 cm. What area remains in square centimeters?
First convert 1.31.31.3 m to 130130130 cm so both dimensions use centimeters.
A room has the outline of a 6.26.26.2 m by 4.74.74.7 m rectangle with a 2.42.42.4 m by 1.51.51.5 m corner removed. All edges meet at right angles. Baseboard covers the entire room boundary except a 0.90.90.9 m doorway on one edge. What length is needed?
A rectangular corner cut replaces equal lengths, so trace the original rectangle perimeter, then omit the doorway.
A 171717 cm by 121212 cm rectangle surrounds a rectangular hole. A border 222 cm wide separates the hole from each of the four outer sides. What is the border area?
Remove 222 cm from both ends of each dimension to find the hole dimensions, 131313 cm by 888 cm.
A trapezoid has parallel bases 151515 cm and 999 cm and perpendicular height 888 cm. A triangular hole of base 666 cm and perpendicular height 555 cm lies strictly inside. What is the retained area?
Use the trapezoid formula with its parallel bases, then subtract the contained triangle.
One yard equals 333 feet. Which conversion and reason are correct?
A square yard measures three feet along each of its two sides.
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