Perimeter/Area: Trapezoids & Triangles
- In general, to find the PERIMETER of a polygon you add the length of each side
- When finding an area of a triangle, remember that in general, the area of a triangle is 1/2 of a rectangle
In this figure the area of the rectangle is 32 cm2, so the area of the triangle would be half...or 16 cm2
- REMEMBER: the height of a shape is the distance from the bottom of the shape to its tops as a straight line
FORMULAS: TRIANGLE
1.) PERIMETER: P(triangle) = s1+s2+s3
remember that perimeter is measured in UNITS (i.e. in., cm, ft, m, etc)
2.) AREA: A(triangle) = 1/2bh
b = length of the base
h= height of the shape
1/2 because a triangle has half the area of a parallelogram
remember that area is measured in UNITS2 (i.e. in2, cm2, ft2, m2, etc)
- When finding an area of a trapezoid, remember that in general, the area of a trapezoid is 1/2 of a parallelogram, and to find the base of the parallelgram you need to add the two bases of the trapezoid. Look at the figure below
- REMEMBER: the height of a shape is the distance from the bottom of the shape to its tops as a straight line
FORMULAS: TRAPEZOID
1.) PERIMETER: P(trapezoid) = s1+s2+s3+s4
remember that perimeter is measured in UNITS (i.e. in., cm, ft, m, etc)
2.) AREA: A(trapezoid) = 1/2(b1+b2)h
b = length of the bases.....a trapezoid has TWO bases
h= height of the shape
1/2 because you have to find the AVERAGE of the two bases
remember that area is measured in UNITS2 (i.e. in2, cm2, ft2, m2, etc)
