How many right angles does a typical parallelogram (a slanted four-sided shape where opposite sides are parallel but no corners form a square corner) have?
A4 right angles, because all four-sided shapes have right angles
B2 right angles, because opposite angles in a parallelogram are always equal
C0 right angles, because the slanted corners are acute or obtuse, not 90 degrees
D1 right angle, at the sharpest corner of the shape
A typical parallelogram (think of a leaning rectangle) has no right angles — its corners are either acute (sharp) or obtuse (wide open), not exactly 90 degrees. Right angles belong to the rectangle family. A rectangle IS a parallelogram, but a special one where all four corners are exactly 90 degrees. Shapes outside the rectangle family — like slanted parallelograms, rhombuses (diamond shapes), or most trapezoids — have no right angles at all.
Question 2 Multiple Choice
You want to check whether a corner on a hand-drawn shape is a right angle. What is the most reliable method?
AEstimate by eye — if the angle looks like a square corner, it is a right angle
BMeasure both sides of the angle and check if they are the same length
CHold the corner of a piece of paper against it — if the paper's edge and the shape's edge line up perfectly, the angle is 90 degrees
DCount the sides of the shape — if it has four sides, all corners must be right angles
The 'corner test' using a sheet of paper works because every corner of a standard piece of paper is a perfect right angle (90 degrees). By placing the paper corner against the shape's angle, you're comparing it to a known right angle. If both edges of the paper align with both edges of the shape, the angle is exactly 90 degrees. Estimating by eye is unreliable for angles near 90 degrees, and side lengths have nothing to do with the angle measurement.
Question 3 True / False
A square is a special type of rectangle, so it also has exactly four right angles.
TTrue
FFalse
Answer: True
A rectangle is defined as a four-sided shape with four right angles. A square is a special rectangle where all four sides are also equal in length. Because a square meets all the requirements of a rectangle — four sides, four right angles — it inherits the four right angles automatically. This is why mathematicians say: 'Every square is a rectangle, but not every rectangle is a square.' The right angles are what make them part of the same shape family.
Question 4 True / False
A triangle can have more than one right angle.
TTrue
FFalse
Answer: False
A triangle's three angles must always add up to exactly 180 degrees. A right angle is 90 degrees. If a triangle had two right angles, those two alone would add up to 180 degrees — leaving zero degrees for the third angle, which is impossible (an angle of 0 degrees means the two sides overlap and there's no triangle). Therefore a triangle can have at most ONE right angle, making it a 'right triangle,' with the other two angles both acute (less than 90 degrees).
Question 5 Short Answer
Describe how you would use a piece of paper to test whether a corner on a drawn shape is a right angle. What does it mean if the shape's edge falls outside the paper's corner?
Think about your answer, then reveal below.
Model answer: Hold one edge of the paper flush along one side of the angle, with the paper's corner at the vertex where the two sides meet. Then look at how the shape's other side lines up with the paper's adjacent edge. If both align perfectly, the angle is a right angle. If the shape's second side falls OUTSIDE the paper's edge (beyond it), the angle is wider than 90 degrees — it is obtuse. If the shape's second side falls INSIDE the paper's edge (between the paper's corner and the shape's side), the angle is smaller than 90 degrees — it is acute.
This method works because the corner of a piece of paper is a reliable, everyday right angle. You are essentially using the paper as a 90-degree measuring tool. The corner test is more accurate than estimating by eye and works without a protractor. It is especially useful for checking corners of hand-drawn shapes, physical objects like furniture, or corners in construction.