Attributes of Shapes — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Which type of angle is smaller than a right angle?
A) Obtuse
B) Right
C) Acute
D) Straight
The correct answer is Acute — these angles measure less than 90 degrees, so the two rays sit closer together than the corner of a square.
2. Which shape always has 2 pairs of perpendicular sides?
A) Trapezoid
B) Rectangle
C) Rhombus
D) Parallelogram
A Rectangle has 4 right angles by definition, and each right angle is formed by a pair of perpendicular sides — that gives exactly 2 pairs in every rectangle.
3. How many vertices does a decagon have?
A) 8
B) 9
C) 10
D) 12
'Deca' means ten, so a decagon has 10 sides, and the number of vertices in any polygon always equals the number of sides — giving 10 vertices.
4. Which statement is true about every parallelogram?
A) It has 4 right angles
B) Opposite sides are parallel and equal
C) All 4 sides are equal
D) It has exactly 1 pair of parallel sides
A parallelogram is defined by its two pairs of parallel sides, and a property that always follows is that those facing sides are also the same length.
Part B: Fill in the Blank
Write the correct answer on each line.
1. An angle that measures more than 90 degrees is called an obtuse angle.
Since 90 degrees is a right angle, anything wider than that opens past the square corner — that wider angle is called obtuse.
2. A rectangle has 2 pairs of perpendicular sides.
Each long side of a rectangle meets each short side at a right angle, so there are 2 pairs of sides that cross perpendicularly to make those square corners.
3. Every rectangle is a parallelogram, but not every parallelogram is a rectangle.
A rectangle is the special kind of parallelogram that adds the rule of 4 right angles, so a slanted parallelogram without right angles cannot be called a rectangle.
4. A regular pentagon has 5 equal angles.
A pentagon has 5 angles, and the word 'regular' means every angle is the same — so a regular pentagon must have 5 equal angles.
5. A polygon with 9 sides is called a nonagon.
The prefix 'nona-' means nine, the same root behind 'November' once being the ninth month, so the 9-sided polygon is named a nonagon.