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Geometry-Formulas-The Basics
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Terms in this set (8)
How do you find the area of a rectangle or square? What is the formula?
You multiply the length by the width.
A = l·w
How do you find the perimeter of a rectangle, square, or triangle? What is the formula?
You add up all of the sides of the figure.
Rectangle/Square: P=2l + 2w (two lengths + two widths)
Triangle: P=a+b+c (the length of each side)
Imagine you walk once completely around the triangle, rectangle, or square. What is that distance you walked? That is your perimeter.
How do you find the area of a triangle? What is the formula?
You multiply the base of the triangle with the height of the triangle, and then multiply that answer by ½.
A=½bh
How do you find the circumference of a circle? What is the formula?
You calculate the total distance around the circle.
C=2πr
Where r=radius.
Example 1: In this diagram, your radius is 9.3, so
C=2π(9.3)
C=18.6π
How do you find the area of a circle? What is the formula?
A=πr²
Where r=radius.
How do you find the midpoint of a segment? What is the formula?
Example: Point A(-2,-1) and Point B(4,2). Find the midpoint of segment AB.
[ (-2+4)/2 , (-1+2)/2) ] Substitute
[ 2/2, 1/2 ] Simplify
(1, 1/2) Midpoint
How do you find the distance between two points? What is the formula?
Example: Point A(-2,-1) and Point B(4,2). Find the distance of segment AB.
d = √[(-2-4)² + (-1-2)²]
d = √[(-6)² + (-3)²]
d = √(36+9)
d = √45
d = 3√5 ≈ 6.7
How do you find the length of one side of a right triangle if it is missing? What is the formula?
Use the Pythagorean Theorem
a²+b²=c²
In this diagram, you are solving for the missing side "b."
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