7.4 Areas of Triangles and Quadrilaterals

Warm-up (IN)1. Find the side length of an equilateral triangle

with perimeter 15.2. Find the side length of a square with

perimeter 36.3. Find the lengths of the legs of an isosceles

triangle with base 12 and perimeter 28.4. Find the lengths of the other sides of a

parallelogram with one side 4 and perimeter 40.

5. Find the height of an equilateral triangle whose sides are 5 units long.

Learning Objective: To find the areas of triangles and quadrilaterals and use the formulas in real world applications

9

5

8

4, 16, 16

About 4.3 units

s

Notes

Learning Objective: To find the areas of triangles and quadrilaterals and use the formulas in real world applications

Area Formulas

Rectangle

2sA

b

hbhA

Square Triangle

b

h

Parallelogram

bhA2

1

b

h bhA

Trapezoid

1b

2b

h

hbbA 212

1

Learning Objective: To find the areas of triangles and quadrilaterals and use the formulas in real world applications

EX 1 – Find the area of an isosceles trapezoid with perimeter 48 in. if the lengths of the bases are 14 in. and 18in.

14

182 2

181448 16

8 822 2h 28

4 2h 642h 60h 152

hbbA 212

1

2

1A 14 18 152

2

1A 32 152

61A 152

1532A 94.123 2in

Learning Objective: To find the areas of triangles and quadrilaterals and use the formulas in real world applications

EX 2 – Find the area of the parallelogram5 ft

13 ft

yd3

17

2132h25

25 2h 1692h 144h 12

bhAydyd

3

22

3

17

yd

ft

1

3 ft22

A 22 12A 2264 ft

CKC p. 363!! On separate paper!

HW – p. 364 #1-7, 10-13, 17-21 odd

Out – The sides of 2 parallelograms are congruent. Must their areas be the same? Explain.

Summary – Today, I learned…POW!!