精选SAT考试几何部分常用公式

Angles Review

Angle CMB = Angle AMD

Angle AMD + Angle CMA = 180o

Example of SAT question with angles:In the figure below, angle AMB is 100o, angle BMD is 40o and angle CME is 60o. What is the value of angle CMD?

Figure not drawn to scale

20o

30o

40o

50o

80o

Answer: If angle AMB is 100o, then angle BME is 180o - 100o = 80o

BMC + CMD = 40o

BMC + CMD + DME = 80o

If we subtract the 2 equations, DME = 40o

CMD + DME = 60o

BMC + CMD + DME = 80o

If we subtract the 2 equations, BMC = 20o

CMD = BME - BMC - DME = 80o - 40o - 20o = 20o

Parallel Lines Review

If the 2 horizontal lines are parallel,

- angles 1 = 3 = 5 = 7 and

- angles 2 = 4 = 6 = 8

Polygons Review

The sum of the measures of the interior angles of a triangle is 180.

a + b + c = 180o

The sum of the measures of the interior angles of a polygon is:

180o

n = number of sides of the polygon.