Answer:
Step-by-step explanation:
a) A square is a rectangle. True
Reason: Property of Rectangle: (i) Opposite sides are equal and parallel. (ii) Each angle is 90 (iii) Diagonals are equal and bisect each other.
A square hold all these properties. A square is a rectangle.
b) A polygon with 21 sides has 432 possible diagonals. False
Reason: Number of diagonals of a polygon =
n --> number of sides of a polygon.
= = 189 diagonals
c) All three angles in an Isosceles triangle are equal. False
Reason: In an isosceles triangle, two angles are equal.
If three angles are equal, then that is an equilateral triangle.
d) The measures of the exterior angles of a nonagon, a nine-sided figure, have a sum of 360°. True.
Reason: The sum of measures of the exterior angles of any polygon is 360