Key Formulas
6.1 Lines and Angles
 
6.2 Triangles
 
6.3 Polygons
 
 
6.4 Circles
 
6.5 Key Formulas
 
Key Formulas
Pythagorean Theorem
a2 + b2 = c2, where a and b are the lengths of the legs of a right triangle and c is the length of the hypotenuse.
Area of a Triangle
Area = 1/ 2 bh, where b is the length of the base and h is the height.
Sum of the Interior Angles of a Polygon
The sum of the interior angles of a polygon is (n – 2)180º, where n is the number of sides in the polygon.
Area of a Trapezoid
Area = h, where s1 and s2 are the lengths of the bases of the trapezoid and h is the height.
Area of a Parallelogram, Rectangle, and Rhombus
Area = bh, where b is the length of the base and h is the height.
Area of a Square
Area = s2, where s is the length of a side of the square.
Circumference of a Circle
Circumference = 2r, where r is the radius of the circle.
Arc Length
Arc length = 2r, where n is the measure of the degree of the arc and r is the radius of the circle.
Area of a Circle
Area = r2, where r is the radius of the circle.
Area of a Sector
Area of sector = r2, where n is the measure of the central angle that forms the boundary of the sector and r is the radius of the circle.
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