Area of Triangles
What is the formula for finding the area of a triangle?
A = 1/2 bh
or
A= bh/2
What is the formula for finding the area of a parallelogram?
A = bh
What's the area of a triangle that has a base of 6 inches and a height of 3 inches?
9 inches2
What's the area of a parallelogram that has a base of 7 inches and a height of 6 inches?
42 inches2
Ben argues that the formula for finding a triangle's area is A = 1/2 bh
Jerry argues that the formula for finding a triangle's area is A = bh/2
Who is correct? Why?
Ben and Jerry are both correct because multiplying by 1/2 is the same as dividing by 2
(Example: 1/2 x 10 = 5 and 10 divided by 2 = 5)
A parallelogram has an area of 50 feet2. If its height is 10 feet, what is its base?
5 feet
A triangle's area is 50 inches2. If its base is 10 inches, what is its height?
10 inches
A parallelogram's area of 144 feet2. Its base is 12 feet, what is its height?
12 feet
What makes a pyramid different from a prism?
Pyramids have all triangular side faces and all faces come together to form a point
A triangle has a base of 20 feet and a height of 5 feet. Bob thinks its area is 100 feet2. Do you agree or disagree? If you disagree, what is its actual area?
Disagree because he multiplied the base and height but forgot to divide by 2. So the actual area is 50 feet2
Explain how the formula for the area of a triangle and parallelogram are related.
(Hint:
Parallelogram: A = bh
Triangle: A = bh/2
They are related because a triangle takes up half the space that a parallelogram does so you have to divide it by 2 (or multiply by 1/2)
Explain why the formula for finding the surface area of cube is 6s2
Because cubes have equal side lengths so you can find the area of one face and then multiply by 6