A parallelogram is a quadrilateral with two pairs of parallel sides. You can choose any side to be the base. An altitude is any segment perpendicular to line containing the base drawn from the side opposite the base. The height is the length of an altitude.
Area of Rectangle= A = bh
Area of a parallelogram = A = bh
Area of a triangle = 1/2bh
Area of a trapezoid = A = 1/2h(b1 + b2)
Area of a rhombus or a kite = A = 1/2 d1d2
Area of a regular polygon = A = 1/2ap - apothem, perimeter
If the scale factor of 2 similar figures is a/b then the ratio of their perimeters is a/b and the ratio of their areas is a^2/b^2
Arc measure- The measure of a minor arc is equal to the measure of its corresponding central angle. The measure of a major arc is the measure of the related minor arc subtracted from 360. The measure of a semicircle is 180.
Arc addition postulate - The measure of the arc formed by two adjacent arcs is the sum of the measures of the two arcs.
Circumfrence of a circle - C = pid or C = 2pir
Arc Length - the length of an arc of a circle is the product of the ratio, measure of arc/360 and the circumfrence of the circle. Length of AB = mAB/360 * 2pir, or mAB/360 * pid
Area of a circle - A = pir^2
Area of a sector of a circle- mAB/360 *pir^2