Construct a rectangle in which one of the diagonals divides the opposite angles into 45° and 45°. What do you observe about the sides?
When a diagonal divides opposite angles into 45° and 45°, the rectangle becomes a square. All four sides are equal in length. Construction: Step 1: Draw a line segment AB. Step 2: At A, construct a line at 45° to AB. Step 3: At B, construct a perpendicular. Step 4: Mark intersection as C. Step 5: Complete the figure. The resulting figure is a square because when the diagonal divides the angles equally (45° each), it indicates that adjacent sides are equal, which is the defining property of a square.
Explanation
The chapter asks students to observe the sides. When a diagonal divides angles into equal parts (45° each), the rectangle must be a square. This is because equal angle division by the diagonal occurs only when adjacent sides are equal, which is the property of a square.
Solution Steps
Step 1: Draw AB.
Step 2: Construct 45° angle at A.
Step 3: Construct perpendicular at B.
Step 4: Find C at intersection.
Step 5: Complete the figure.
Step 6: Observe that all sides are equal - it's a square.