Basic Geometry Formulas – Math (0301) Emporium
A quadrilateral is a four‐sided polygon. Parallelograms, rectangles, squares, rhombus, and trapezoids are all quadrilaterals. The diameter of a circle is a line segment across the circle through the center. The radius of a circle is a line segment from the center of the circle to a point on the circle. Diameter
Radius
NOTE:
π ≈ 3.14 or
π≈
22
7
Perimeter is the distance around a figure. The distance around a circle is called circumference. Area is the inside measure of a figure. Volume is the amount of space inside a figure. Surface Area is the total area on the surface of a figure. When calculating the perimeter of composite figures, BE CAREFUL! You have to deduct the measurement of one of the shared‐sides from one of the formulas. If you don’t, you’ll end up calculating the same side twice. Area2 Perimeter Volume3
Surface Area2
Triangle: P = a + b + c
Triangle: A =
1
bh
2
Rectangle: P = 2L + 2W Rectangle: A = LW
P = 4s
Square:
Square: A = s2
Circle:
C = πd or C = 2πr
Rectangular Solid
V = LWH
Cube: V = s3
Rectangular Solid
SA = 2LW + 2LH + 2WH
Cube:
SA = 6s2
Sphere
4
V = πr3
3
Sphere
SA = 4 πr2
Circle:
A = πr2
Right Circular Cylinder
V = πr2h
Right Circular Cylinder
SA = 2 πr2 + 2 πrh
Parallelogram
A = bh
Right Circular Cone
1
V = πr2h
3
Right Circular Cone
Trapezoid:
1
A= (b1 + b2)h
2
Regular Pyramid
1
V = s2 h
3
Pythagorean Theorem
a2 + b2 = c2
c
a
b
The Pythagorean Theorem is used to find the length of the sides of a triangle. Exact = π
Approximate = “Do the Math”
SA  π  r  r 2  h 2  π  r 2
Square-Based Pyramid
1
SA  B  pl
2
B = area of base
p = perimeter of base
h = height
s = side
l = slant height
Regular Pyramid
SA = s2 + 2sl
Trapezoid
SA = (b1 + b2)h + pH
h = the height
H = the length of the longest base
Saved: EPCC (Math Emporium) Geometry Formulas 1 (Microsoft Word) c.Hines