Just like any other subject in math, Geometry is
loaded with a wide variety of subtopics  including
the ubiquitous Trigonometry. Just as the previous
pages however, we will focus on the basics  again
to help stir the memory a bit.The basic form of
Geometry  that is lines, perimeters, areas  is
called Euclidean Geometry named after its Greek
inventor, Euclid. Another name for Euclidean
Geometry is Plane Geometry.
The section will only cover:
Perimeter, Area, and Volume
Angles
Basic
Trigonometric Functions
Perimeter, Area, and Volume:
A perimeter is the length around the outside of
any geometric shape. Simply add the lengths of the
sides together.
Area is the measure of space inside any
twodimensional geometric shape.
Volume is the measure of space inside any
threedimensional geometric shape.
Area of a triangle:
Area of a rectangle and parallelogram:
The Circle:
The circumference of a circle is the same as the
perimeter of a triangle or rectangle. To find the
circumference:
r = radius of a circle
π = pi
= 3.14
The
area of a circle:
Three dimensional objects:
Area of the rectangle solid:
Angle of the cylinder:
Area of a Sphere:
Volume of a Sphere:
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Angles:
Complimentary Angles:

Two angles are complimentary when the
sum of their angles is 90^{o}. In
the image on the left, angles A and B are
complimentary and angles A and C are also
complimentary. 

The remaining angle
definitions will use the image above. 
Supplementary Angles:
Two angles are supplementary is the sum of the
angles is 180^{o}. Angles 1 and 2 as well as
angles 2 and 4 are supplementary angles.
Opposite (Vertical) Angles:
The intersection of two lines (m1 and m3) form 4
angles. Opposite angles are equal (congruent).
Angles 1 and 4 as well as angles 2 and 3 are
congruent.
Alternate Angles:
Lines m1 and m2 are parallel. Angles 4 and 5 are
alternate interior angles and are congruent. Angles
3 and 6 are also interior angles but are not
congruent. Angles 2 and 7 are alternate exterior
angles and are congruent. Angles 1 and 8 are also
alternate exterior angles but are not congruent.
Triangles:
The three angles of a triangle always total 180^{o}.
An equilateral triangle is a triangle with 3 equal
sides and all 3 angles are 60^{o}.
An isosceles triangle is a triangle with
two equal angles. The two equal angles must
each be less than 60^{o}. The image
on the left illustrates angles A and B are
equal. 

The height of a triangle is defined by the base.
Once any side of a triangle is chosen, the angle
between the base and height can change, but the but
measure of the height remains the same.
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Basic
Trigonometric Functions:
Trigonometry is a specialty of Geometry that
focuses mostly on angles. If we want the sum of all
internal angles or if we want a ratio of angles for
example, we will turn to Trigonometry.
Two recurrent terms to know are the Sine and
Cosine
 Sine = ratio of the height to the hypotenuse
(see image below)
 Cosine = ratio of the base of the hypotenuse
(see image below)
A simple example: A straight line has an angle 
its 0 degrees.
Sine = 0^{0}
Cosine = 1^{0}
To introduce the working formulas
for Sine and Cosine, we will use a right triangle.
Pythagorean Theorem:
Sum of Interior Angles:
where n = the number of sides in the shape of the
object
Grade and Percent Grade:
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