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Parallelogram

quadrilateral with both pairs of opposite sides congruent and parallel, opposite angles congruent, diagonals bisect each other,

Rhombus

parallelogram w/ 4 congruent sides, diagonals bisect angles, diagonal perpendicular

Rectangle

parallelogram w/ 4 right angles, diagonals congruent

Square

rhombus and rectangle therefore 4 congruent sides and 4 right angles, congruent perpendicular diagonals, diagonals bisect angles

Kite

quadrilateral, two pairs of adjacent sides congruent,, no opposite sides congruent, side angles congruent, diagonals are perpendicular, short one bisected, angles bisected

Trapezoid

quadrilateral w only 1 set of parallel sides

Isosceles Trapezoid

nonparallel sides congruent, adjacent angles congruent, diagonals congruent

3+ parallel lines

congruent segments of transversal

Similarity

AA~, SAS~ SSS~

Geometric mean

a/x=x/b any 2 positive numbers

altitude of a right triangle

makes 2 similar triagnles

side splitter thm

if a line is parallel to one side of a triangle and intersects with the other two sides then it divides those sides proportionally

Angle bisector thm

if a ray bisects an angle of a triangle then it divides the oposide side into town segmeents that are proportional to the other two sides

Pythagorean Thm

a^2+b^2= c^2

45-45-90

hypotenuse is sqrt2(leg)

30-60-90

x, x(sqrt3), 2x

Vector

magnitude and direction (degree, Direction, distance)

Area of Parallelogram

b(h)

Area of Triangle

1/2bh

Area Trapezoid

1/2h(b1+b2)

Area of Rhombus or Kite

1/2d1(d2)

Area of Regular Polygons

1/2ap

Area of any triangle

1/2bcsineA

Perimeters and Areas of Similar Figures

P=a/b A=a^2/b^2 (RATIOS)

Measure of Central Angle

360/n

Radius

center to circumference

Area of Circle

(pi)r^2

Surface Area Prism

ph+2B

Surface Area Cylinder

2(pi)rh+ 2(pi)r^2

Surface Area Pyramid

1/2pl+B

Surface Area Cone

(pi)rL+(pi)r^2

Volume of Prism

V=Bh

Volume of Cylinder

(pi)r^2h

Volume of Pyramid

1/3Bh

Volume of Cone

1/3(pi)r^2h

Tangent

line that intersects at only one point on circle

Chord

segment with endpoints on circle

Secant

intersects at 2 places

coordinate plane circles

(x-h)^2+(y-k)^2=r^2

Distance formula

sqrt[(x2-x1)^2+(y2-y1)^2]