Download ACT Geometry Review Sheet

ACT Geometry Review Sheet
The Fab Five:
1) Pythagorean theorem,
2) Angles in a triangle add to 180,
3) Linear angles (pairs, triples, etc),
4) Base angles of an isosceles triangle are congruent
5) Tangent and a radius are 
*Use other problems to help---ie,. mABC, which means “measure of angle ABC” is similar to mAB which
means “measure of arc AB”
Angles:
notation, vertex
supplementary, complementary
Adding to 180o ie. linear pairs
Vertical angles
Adding to 90o ie acute angles in a rt triangle
360o
*just because something looks like it is being split in two, don’t assume
this!!!!!.........ex. a 90° with a split is not necessarily a 45°,45° split
exceptions: squares, equilateral triangles, isosceles triangles, regular hexagons

Parallel lines: notation
The big three
1) Alternate interior angles
2) Corresponding angles
3) Same side interior angles
Similar triangles:
corresponding parts are in proportion,
therefore set up proportions.
A
6
B
E
8
Proving: AA, SSS, SAS
x
C
Parallelograms:
Opposite sides are parallel
Opposite angles are congruent
Opposite sides are congruent
Diagonals bisect each other
12
D
square; rectangle; rhombus
Trapezoids:
*4 sided figure with one set of parallel lines.
*With isosceles trapezoid—can guess on bisecting angels, congruent sides etc.
Right triangles:
a2 + b2 = c2
***
30: 60 : 90
**** 45 : 45 : 90
***
SOHCAHTOA  to find angle,
use sin-1

Circles:
 radius and tangent line
1) Angle at center = arco
2) Angle on the circle = ½ arco
 equation of a circle
(x - h)2 + ( y – k )2 = r2
Perimeter; Area; Volume, Surface Area, "Similarity"
Be creative!!!
Specials usually not on formula sheets: Area of rhombus/ square involving diagonals
Area of an equilateral triangle
Algebra tool kit
 #1….Substitution!!!!!!
 Factoring / FOIL ---- difference of 2 squares, trinomials………set = 0 to solve an equation
 Graphing ----- make a T chart ….. ex. y = x2
 Exponent rules ------ Multiplying with like bases, add exponents
Exponent to exponent, multiply exponents
 Absolute Values --- if an equation, set up two equations
 Inequalities ---- solve as equals, flip symbol when mult or div by "-"
 Square roots ---- perfects squares undo, jail break,
*when on you put it on a variable in equation  other side is ±
 solving proportions
 y = mx + b, y – y = m( x – x ), m 
 midpoint formula,
yy
, parallel, perpendicular
xx
distance formula
 quadratic formula….used to find roots of a quadratic…..look at multiple choice to see if using
 No zero on bottom of fraction!!!!!!!
Misc: integers, rational numbers, consecutive numbers, approximating sq rts., i, benchmarks as reference