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Basic Geometry Formulas
Basic Geometry Formulas
A quadrilateral is a four-sided polygon. A parallelogram, a rectangle, a square , a rhombus, and a trapezoid are all quadrilaterals.
A circle is a plane figure in which all points are the same distance from the center of the circle. A diameter of a circle is a line segment across the circle through the center. A radius of a circle is a line segment from the center of the circle to a point on the circle.
The perimeter of a plane geometric figure is a measure of the distance around the figure. The distance around a circle is called the circumference. Area is the amount of surface in a region. Volume is a measure of the amount of space inside a figure in space. The surface area of a solid is the total area on the surface of the solid.
When calculating perimeter of composite figures Be Careful!!!!! In most cases, when calculating the perimeter of a composite figure, you have to deduct one of the sides in your formulas. If you don’t, you’ll end up calculating the same side.
|Triangle:||P = a + b + c|
|Rectangle:||P = 2L + 2W|
|Square :||P = 4s|
|Circle :||C = πd or C = 2πr|
|Triangle:||A = 1/2bh|
|Rectangle:||A = LW|
|Square :||A = s2|
|Circle :||A = πr2|
|Parallelogram:||A = bh|
|Trapezoid||A = 1/2h (b1 + b2)|
|Rectangular solid:||V = LWH|
|Cube :||V = s3|
|Sphere:||V = (4/3)πr3|
|Right circular cylinder:||V = πr2h|
|Right circular cone:||V = (1/3) πr2h|
|Regular pyramid:||V = (1/3)s2h|
|Rectangular solid:||SA = 2LW + 2LH + 2WH|
|Cube :||SA = 6s2|
|Sphere:||SA = 4 πr2|
|Right circular cylinder:||SA = 2 πr2 + 2 πrh|
|Right circular cone:||SA = πr2 + πrl|
|Regular pyramid:||SA = s2 + 2sl|
|Trapezoid||SA = (b1 + b2)h + pH (H = length of the longest base)|
It can be used to find the length of the sides of a triangle and the distance or height between two points . If a and b are the legs of a right triangle and c is the length of the hypotenuse, then a2 + b2 = c2
The ratios of corresponding sides are equal. The ratio of corresponding heights is equal to the ratio of corresponding sides.
< 1 = < 4 and < 3 = < 5 because they are alternate interior angles
The measure of an arc equals the measure of the central angle.
Arc length = measure of central angle circumference
Measure of central angle =
The central angle is < ABC. The arc is AC