Geometry Concepts:GRE°
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50 terms
Terms | Definitions |
|---|---|
 ∏ = | 3.14 |
| √2= | 1.4 |
| √3= | 1.7 |
| The point of intersection for an angle is | a vertex |
| the sum of the measures of the angles on one side of a straight line = | 180° |
| the sum of the angles around a point = | 360° |
| supplementary angles make a straight angle | 60° +120°=180° |
| complementary angles make up a right angle | 30° +60°=90° |
| bisect means | to split a line or angle into two equal lines or angles |
| verticle angles | are opposite angles of two intersecting lines |
| each verticle angle is supplementary to | each of its adjacent angles |
| When two parallel lines intersect with a third line | all acute angles formed are equal, all obtuse angles formed are equal, and any acute angle is supplementary to any obtuse angle |
| If a line gets higher as you move to the right, it has a ______ slope | positive |
| If a line goes down as you move to the right, it has a _______ slope | negative |
| Slope = | rise/run = change in y / change in x |
| Rise means | the differnce between the y-coordinate values of the two points on the line |
| Run means | the difference between the x coordinate values of the two points on the line |
| Slope intercept form is | y=mx + b (m is the slope, b is the y intercept point) |
| Triangle angles = ______° | 180 |
| Altitude = | height of a triangle |
| The length of any side of a triangle is _______ than the sum of the other two sides | less |
| In triangles, the greater angles lie opposite the _______ ______. | longer sides |
| Area of a triangle = | 1/2 base x height |
| Area of a right triangle= | 1/2 lenght1 x length2 |
| Perimeter of a polygon= | distance around the polygon |
| Isosceles triangle are | triangles that have two sides (and hence two angles ) that are equal. |
| Equilateral triangles are | triangles that have three sides (and three 60° angels) othat are equal. |
| Similar triangles are | the same shape |
| Congruent triangles are | the same shape and size |
| The ratio of the areas of two similar triangles is | the SQUARE of the ratio of the corresponding lengths |
| Right triangles have | 2 legs (a and b) and a hypotenuse (c) |
| Pythagorean theorum states | a² + b² = c² |
| Pythagorean triplets are | right triangles with sides 3,4,5 (6,8,10, or 9,12,15)and 5,12,13 and 7,24,25 and 9,40,41 and 11,60,61 |
| Pythagorean special combos are | right triangles with sides 1,1,√2 for isosceles right) and 1,√3,2 (for 30,60,90 triangles) |
| Quadrilateral is | a four sided polygon with angles that equal 360° |
| For Squares: Area = side squared or | √Area = side |
| For similar figures: The ratio of areas = the ________ of the ratio of lengths | square (ex. 25/36 =5sq./6sq.) |
| Area of a circle = | ∏r² |
| A chord is | a line segment joining 2 points on a circle |
| A line drawn tangent to a circle is | is perpendicular to the radius at the point of tangency |
| A circumference of a circle = | ∏d or 2∏r |
| ∏ is the ratio of | the circle's circumference to it's diameter or C/D |
| An arc is a | portion of the circumference of the circle and equals the degrees of the angle |
| A minor arc is the small arc of a circle. A major arc is the _____ arc of a circle | larger |
| Arc length = | (angle/360°)(circumferance) or angle/360° x 2∏r |
| A sector is | a pie shaped portion of a circle |
| Area of a sector= | (angle°/360°)(∏r²) |
| Inscribed shapes are | inside another shape and all the vertice touch the edge of the outside shape |
| Circumscribed shapes are | outside another shape and all the vertices touch the edge of the inside shape |
| A triangle circumscribed in a half circle is a ________ triangle | right |
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