11.2 Triangles and Parallelograms

11.2 Triangles and Parallelograms

T100: The area of a parallelogram is equal to the product of the base and the height.

A = bh

b

h

Find the area of MATH

AM

TH

13cm

9cm

6cm

Why is the Area = bh?

M

TH

13cm

9cm

6cm

A = bh

= 13(6)

= 78cm2

You will receive one point for each line, plus the correct unit. Minimum 3 lines.

A

T101: The area of a triangle is equal to one-half the product of a base and the height (or altitude) for that base.

A = bh

Where b is the length of the base and h is the altitude. Altitude may be inside, outside or the leg of the triangle. The base may not always be at the bottom.

1

2

b

h

8mm

12mm Find the area of this triangle.

Find the base of a triangle with an altitude of 15 and area 60.

x

15

x

15Find the base of a triangle with an altitude of 15 and area 60.

Find the area of a parallelogram whose sides are 14 and 6 and whose acute angle is 60˚. Draw and label.

614

60˚

How will you find the height?

UD

CK

614

60˚

D U

CK S

Drop line DS to form a 30-60-90 triangle.Line DS is

3 3

A = bh

= 14( )

= 42

3 3

3

The diagonals of a kite are 10 and 24. Find the kite’s area.

Draw the shape, label. What shapes do you have to use? Write the formula needed and solve.

Assignment:

Make your own area problem! Come up with creative picture (ex: fish, bird, house) that involves at least 4 different shapes (circles, rectangles, parallelograms, triangles). Write a rough draft and then a final draft on the construction paper. Leave room on your final draft for someone to solve your problem. You have 15 minutes to come up with the problem

When finished: Pass your problem to the person behind you to calculate the area!

Get the homework done so you don’t have any over the break!

Pg 519 #2-20 Evens