Geometry Case

Geometry

Some facts:

• Line is 180-degree angle.
• At two line intersection, four angels are formed and their sum is 360 degrees.
• When two perpendicular lines intersect, they form four 90-degree angles.
• 90-degree angels are also called right angles.
• 3 angles inside a triangle equal 180 degrees.
• 4 angles inside any four-sided figure add up to 360 degrees
• A circle contains 360 degrees.

Vertical angels and Parallel lines

Vertical angels are angles across from each other

Parallel lines never intersect

Triangles

Equilateral Triangles

Isosceles Triangles

Note: In any triangle, the longest side is opposite the largest interior angle; the shortest side is opposite the smallest interior angle.

Perimeter of a Triangle: Sum of all sides.

The Third Side Rule: The length of any side of triangle must be less than the sum of the other two sides and greater than the difference between the other two sides.

Area of a Triangle: ½ * base * height

Pythagorean Theorem: c2 = a2 + b2

Right isosceles triangle:  x : x : x√2

30:60:90 Triangles: x : x√3 : 2x

Side opposite to 60 degree angle is x√3

Side opposite to 30 degree angle is x

Perimeter of rectangle and square: Sum of all sides.

Circles:

Area of circle: π * r2

Circumference of circle:  2 πr

The coordinate system: The horizontal line is called x-axis and the vertical line is called y-axis.

Quadrant I =

Quadrant II =

Quadrant III =

Quadrant IV =

Equation of line = y = mx + b