Quadrilaterals
Classifying Quadrilaterals
A quadrilateral is a closed figure with four sides that are line segments. The figures below are special types of quadrilaterals.
Example
Classify the quadrilateral.
Solution:
The quadrilateral is a parallelogram with 4 sides of equal length. So, it is a rhombus. It is also not a square because the angles are not right.
Finding Unknown Angle Measures in a Quadrilateral
The sum of the angle measures in a quadrilateral is 360 degrees. If one angle measurement is unknown, algebra can be used to solve for the missing angle measure.
Example
Find the value of x.
Solution:
Recall that the sum of the angle measures in a quadrilateral is 360 degrees.
Guided Practice (Ask your tutor for help.)
1. Classify the quadrilateral.
2. Complete each statement.
a. A _?_ is a quadrilateral with both pairs of opposite sides parallel.
b. A parallelogram with 4 right angles is a _?_.c. A _?_ is a quadrilateral with exactly 1 pair of parallel sides.
3. Classify the quadrilateral.
4. Which word can describe two adjacent sides of a rectangle?
A. vertical
B. right
C. acute
D. perpendicular
5. Three angles in a quadrilateral are acute. Classify the fourth angle.
A. acute
B. right
C. obtuse
D. straight
6. Is statement below is always, sometimes, or never true?
a. A rhombus is also a parallelogram.
b. A rectangle is also a square.
c. A square is also a parallelogram.
d. A triangle is also a quadrilateral.
e. A quadrilateral is also a rectangle.
7. Find the value of x.