Angles of Polygons
What is the formula to solve for the sum of interior angles?
S = (n-2) x 180
The sum of interior angles in a triangle...
180 degrees
The sides of similar figures are ____________
proportional
Factor: x2 + 12x + 27
(x+9)(x+3)
The sum of exterior angles for ANY polygons is....
360 degrees
How many degrees is EACH angle in an EQUILATERAL triangle?
60 degrees
How do you solve proportions? What method?
Cross multiply
Factor: x2 - 1x - 20
(x + 4)(x - 5)
What is the sum of the interior angles of a 35-gon?
5940 degrees
If the three angles in a triangle are:
<1 = 2x
<2 = x + 1
<3 = 20
Find the value of x.
x = 53
What are the three methods for proving that triangles are similar? (think about the initials/acronyms)
AA, SSS, SAS
Factor: 2x2 +3x - 9
(x + 3)(2x - 3)
What is the measure of EACH interior angle of a regular decagon?
144 degrees
<1 and <2 are remote angles (non-adjacent interior), <3 is an exterior angle.
If <1 = 11x - 2
<2 = 9x + 1
<3 = 19x + 3
Find the value of x.
x = 4
Factor and solve:
x2 + 2x - 15 =0
x = -5, 3
Find the number of sides of a polygon whose sum of interior angles is 6660 degrees.
39 sides
Triangle ABC is an isosceles triangle where <B is congruent to <C. If AB = 4x + 17, BC = 7x - 5, AC = 16x - 67, find the value of AB.
AB = 45
Factor and solve:
3x2 - 8x = -4
x = 2
x = 2/3 (0.666)