One leg is 7 + 9 = 16, and the other leg is 12. The resulting triangle of which is the hypotenuse is
another 3-4-5 triangle (times 4). = 20, and the answer is (C).
SPECIAL QUADRILATERALS
The trapezoid is just one of five special quadrilaterals you need to be familiar with. As with triangles,
there is some overlap among these categories, and some figures fit into none of these categories.
Just as a 45-45-90 triangle is both right and isosceles, a quadrilateral with four equal sides and four
right angles is not only a square but also a rhombus, a rectangle, and a parallelogram. It is wise to
have a solid grasp of the definitions and special characteristics of these five quadrilateral types.
Trapezoids: A trapezoid is a four-sided figure with one pair of parallel sides and one pair of
nonparallel sides.
Think of this formula as the average of the bases (the two parallel sides) times the height (the length
of the perpendicular altitude).
In the trapezoid ABCD above, you can use side AB for the height. The average of the bases is
, so the area is 8 × 5, or 40.
Parallelograms: A parallelogram is a four-sided figure with two pairs of parallel sides. Opposite
sides are equal. Opposite angles are equal. Consecutive angles add up to 180°.
Area of Parallelogram = base × height