11-2 Areas of Trapezoids, Rhombi, and Kites

1
11-2 Areas of Trapezoids, Rhombi, and Kites
You found areas of triangles and parallelograms.

• Find areas of trapezoids.

• Find areas of rhombi and kites.

2
Definitions

• A rhombus is a quadrilateral with four congruent
  sides.
• (All rhombuses are parallelograms.)
• A trapezoid is a quadrilateral with exactly one
  pair of parallel sides. The parallel sides are
  the bases of the trapezoid, and the nonparallel
  sides are its legs.

3
Classify each quadrilateral as a square,
rectangle, rhombus, parallelogram or trapezoid.
rectangle, parallelogram
trapezoid
square, rectangle, rhombus, parallelogram
trapezoid
rhombus, parallelogram
4

• The area of a trapezoid is the product of half
  the sum of the bases (b1 and b2) and the height
  (h).

5
Find the area of the trapezoid
37.125
47.5 cm2
30
6
SHAVING Find the area of steel used to make the
side of the razor blade shown below.
Area of a trapezoid
h 1, b1 3, b2 2.5
Simplify.
Answer A 2.75 cm2
7
Find the area of the side of the pool outlined
below.
A. 288 ft2 B. 295.5 ft2 C. 302.5 ft2 D. 310 ft2
8
Definitions

• Rhombus a quadrilateral with all four sides
  congruent.
• Kite a quadrilateral with exactly two pairs of
  consecutive congruent sides.

 
 
 
 
9
The area of a rhombus or kite is ½ of the product
of diagonal 1 and diagonal 2.
 
p. 791
10
A. Find the area of the kite.
Area of a kite
d1 7 and d2 12
Answer 42 ft2
11
Area of a Rhombus and a Kite
B. Find the area of the rhombus.
Step 1 Find the length of each diagonal.
Since the diagonals of a rhombus bisect
each other, then the lengths of the
diagonals are 7 7 or 14 in. and 9
9 or 18 in.
Step 2 Find the area of the rhombus.
Area of a rhombus
d1 14 and d2 18
Answer 126 in2
12
A. Find the area of the kite.
A. 48.75 ft2 B. 58.5 ft2 C. 75.25 ft2 D. 117 ft2
13
B. Find the area of the rhombus.
A. 45 in2 B. 90 in2 C. 180 in2 D. 360 in2
14
Area Formulas
p. 792
15
11-2 Assignment
Page 793, 8-16 No formulas with numbers in it, no
credit