- A90
- B81
- C99
- D180
Step-by-Step Solution
Adjacent angles are supplementary, so → → °. (Such a parallelogram is a rectangle.)
Answer: A) 90
Two adjacent angles of a parallelogram are equal. What is the measure of each, in degrees?
Class 8Understanding QuadrilateralsQuadrilaterals
Key idea: Special parallelograms — extra properties
**Rectangle**: parallelogram + all angles 90°. Extra: diagonals are equal in length.
**Rhombus**: parallelogram + all sides equal. Extra: diagonals are perpendicular AND bisect the angles at each vertex.
**Square**: parallelogram + all angles 90° + all sides equal. Has both extras: equal AND perpendicular AND angle-bisecting diagonals.
Knowing the family tree saves you memorising overlapping rules — a square inherits everything from rectangle AND rhombus.
**Rhombus**: parallelogram + all sides equal. Extra: diagonals are perpendicular AND bisect the angles at each vertex.
**Square**: parallelogram + all angles 90° + all sides equal. Has both extras: equal AND perpendicular AND angle-bisecting diagonals.
Knowing the family tree saves you memorising overlapping rules — a square inherits everything from rectangle AND rhombus.
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