Area of Parallelograms and Circles#33

VOCABULARY (circles)

• The decimal representation of pi or starts with 3.14159265 . . . and goes on forever without repeating. Most people estimate using either 3.14 or 22/7.

• Part of a CircleRadius

Circumference C = d, or C = 2r

CenterChord

Diameter

VOCABULARY

• A polygon is a closed figure formed by 3 or more straight lines.

• A parallelogram is a quadrilateral with opposite sides parallel and opposite sides the same length.

• A rhombus is a parallelogram with four equal sides.

• The area of a parallelogram (A=bh) is the product of its base b and its height h.

• The base of a parallelogram can be any one of its sides.• The height of the parallelogram is the perpendicular

distance from the base to the opposite side.• A formula is an equation that shows a relationship

among certain quantities.

You can use the formula for the area of a rectangle to write a formula for the area of a parallelogram. Imagine cutting off the triangle drawn in the parallelogram and sliding it to the right to form a rectangle.

The area of a parallelogram = bh. The area of a rectangle = lw.

The base of the parallelogram is the length of the rectangle. The height of the parallelogram is the width of the rectangle.

FYI

I DO

1)Find the area of the parallelogram.

2) Estimate the area of the circle. Use 3 to approximate .

20 m

8 cm

6 cm

WE DO

1) Find the area of the rectangle..

11 ft.

7 ft.

2) Find the area of the parallelogram.

1 ft14

2 ft12

3) The figure shows a wall of an office with three identical windows. An employee is going to paint this wall of the officeWhat is the area that will be painted?

3 ft

10 ft8 ft

2 ft

4) Find the area of the circle. Use 3.14 for .

yd 8

YOU DO

1) Find the area of the figure.15 in.

9 in.

2) Find the missing dimension of the figure.

3) Estimate the area of the circle. Use 3 to approximate .

9 in.

A=45 in²