Areas of Parallelograms,

Triangles, Trapezoids, Rhombuses and Kites

Essential Understanding

You can find the area of a parallelogram or a triangle when you know the length of its base and its height

You can find the area of a trapezoid when you know its height and the lengths of its bases

Students will be able to find the area of parallelograms and triangles.

Students will be able to find the area of trapezoids, rhombuses, and kites.

Area of a Rectangle

Area = base times height

A = bh

Area of a Parallelogram

Parallelogram: opposite sides are parallel and opposite angles are equal

A = bh

Base of a parallelogram can be any of its sides

Altitude: a segment perpendicular to the line containing the base

Height is the length of the altitude

Area of a Trianlge

You can rotate a triangle about the midpoint of a side to form a parallelogram

The area is half the area of a parallelogram

A = ½ b h

Base is any of its sides

Height is the length of its altitude

Area of a Trapezoid

A = ½ h(b1 + b2)

Height is the perpendicular distance between the bases

the bases are the parallel sides

Area of a Rhombus or Kite

A = ½ d1 d2

d stands for the diagonals of the figures

Parallelograms

What is the area of a parallelogram whose base has length 12m and height 9 m?

A parallelogram has sides 15 cm and 18 cm. The height corresponding to a 15 cm base is 9cm. What is the height corresponding to an 18 cm base?

Trapezoids

What is the area of a trapezoid with height 7 cm and bases 12 cm and 15 cm?

Kite/Rhombus

What is the area of a kite with diagonals 12 in and 9 in?

A rhombus has sides 10 cm long. If the longer diagonal is 16 cm, what is the area of the rhombus?

Homework

Pg. 619

# 8 – 16 even, 17, 42 (8 problems)

Pg. 626

# 12 – 24 even, 34, 38 (9 problems)

17 problems total