2. Trapezoids A quadrilateral with exactly one pair of parallel sides is called a trapezoid.

3. Parts of a trapezoid The parallel sides are called bases. The other sides are called legs. base leg

4. ISOSCELES TRAPEZOID A trapezoid with congruent legs is called an isosceles trapezoid. What is true of the base angles? (2x + 10) o (-5x + 80) o (2x + 10) o = (-5x + 80) o = +5x +5x 7x + 10 = 80 - 10 =- 10 7x = 70 x = 10

5. Find the missing values. 5x + y = 14 15x + 7y = 58 -3(5x + y = 14) 15x + 7y = 58 -15x - 3y = -42 15x + 7y = 58 4y = 16 y = 4 5x + 4 = 14 - 4 = - 4 5x = 10 x = 2

6. Median of a Trapezoid The median of a trapezoid is a segment that joins the midpoints of the legs. The median of a trapezoid is 1) Is parallel to the bases 2) Has a length that is equal to average of the base lengths. 10 30 x 10 + 30 2 = x x = 20

7. Median of a Trapezoid Find the missing values. 4x + 1 11x - 2 37 (4x + 1) + ( 11x – 2) 2 = 37 (4x + 1) + ( 11x – 2) = 74 15x – 1 = 74 15x = 75 x = 5

8. Complete worksheet.