Example 1
Which of the following figures is a quadrilateral?
Example 2
Which of the following figures is a quadrilateral?
Example 3
Identify the opposite sides in quadrilateral ABCD.
Example 4
In the quadrilateral shown, ∠A measures 90°, and ∠B and ∠C each measure 30°. What is the measure of ∠D?
Example 5
A quadrilateral has angles that measure 130°, 60°, and 70°. What is the measure of the remaining angle?
Example 6
A quadrilateral has an angle that measures 150°. Its remaining three angles are all congruent. What are the measures of these three angles?
Example 7
The four angles of a quadrilateral are given by the expressions 68 + x, 12x – 21, 3x + 7, and x. What are the measures of each of these angles?