Different Types of Triangles

Type of Triangle based on Sides Characteristics
Equilateral All sides are of the same dimension
Scalene No equal sides
Isosceles Two equal sides
Types of Triangles based on Angles Characteristics
Acute All angles are less than 90 degrees
Right-angle Has an angle equal to 90 degrees
Obtuse Has an angle greater than 90 degrees

Pythagorean Theorem

A way to find the side lengths in a right triangle.

a=side #1

b=side #2

c=side #3

Formula-

Trigonometric Ratios

θ=theta

theta= given angle of the right triangle

O=opposite side from theta

A=adjacent side from theta

H=hypotenuse (longest side) of the triangle

Trig Ratio Names Ratio
Sin(θ) O/H
Cos(θ) A/H
Tan(θ) O/A
Cot(θ) A/O
Sec(θ) H/A
Csc(θ) H/O

Area of different triangles with different terms 

Area of an equilateral triangle

A=area

a=side

Area of a triangle with all 3 sides but not the height

s=semi-perimeter (half of the perimeter)

a=side #1

b=side #2

c=side #3