Area of triangles, polygons, and trapezoids- TEST REVIEW

Area of triangles, polygons, and trapezoids- TEST REVIEW

Multiple Choice

How do you find the area of a triangle?

• multiply base x height

• 1. multiply base x height
  2. divide the answer by 2

• 1. add base 1 and base 2
  2. multiply the answer by the height
  3. divide the answer by 2

Area of Triangles

You have two problems to solve!  

1.  Multiply the base x the height.
2. Divide your answer by 2.  

We divide by 2 because a triangle is half the size of a rectangle.  

Area of a Triangle

The base of this triangle is 6 cm.  The height of the triangle is 5 cm. We DO NOT use the 8 cm measurement because that side is not perpendicular to any of the other sides.

6 x 5 = 30 then divide by 2 to get 15 cm^2.

Multiple Choice

What is the area of the triangle?

• 17 sq. units

• 20 sq. units

• 27 sq. units

• 32 sq. units

Multiple Choice

How do you find the area of a trapezoid?

• multiply base x height

• multiply base x height divide the answer by 2

• add base 1 and base 2 multiply the answer by the height divide the answer by 2

Area of Trapezoids

 Add base 1 and base 2. Multiply your answer by the height. Divide your answer by 2.

Area of Trapezoids

To find the area of a trapezoid, I can use 12 in. as BASE 1 and 24 in. as BASE 2. The height of my trapezoid is 14 in. because it forms a perpendicular line segment with the bases.

ADD base 1 and base 2; 12+24=36

MULTIPLY answer by the height; 36X14=504

DIVIDE 504 / 2= 252 IN.^2

Multiple Choice

• 19 ft²

• 35 ft²

• 45 ft²

• 50 ft²

Area of Polygons

A polygon is a closed, two-dimensional shape with straight sides that do not cross each other.

Area of Polygons

1. Figure out how to decompose the polygon.
2. I would decompose so I have a triangle on top and a trapezoid on the bottom.
3. Triangle base- 9 units; height- 4 units (9x4=36; 36/2=18 sq. units)
4. Trapezoid b1- 9 units; b2- 7 units; height- 3 units (9+7=16; 16x3=48; 48/2=24 sq. units)
5. ADD triangle area and trapezoid area (18 + 24 = 42 sq units)

Multiple Choice

• 90 units²

• 84 units²

• 72 units²

• 62 units²

Multiple Choice

• 50 cm²

• 56 cm²

• 69 cm²

• 94 cm²

Multiple Choice

• 8 in²

• 9 in²

• 10 in²

• 12 in²

Multiple Choice

• 27 square yards

• 81 square yards

• 98 square yards

• 162 square yards

Multiple Choice

What is the area of the polygon?

• 24 square inches

• 60 square inches

• 84 square inches

• 168 square inches