All GRE Math Resources
Example Questions
Example Question #1 : How To Find An Angle In An Acute / Obtuse Triangle
The three angles in a triangle measure 3x, 4x + 10, and 8x + 20. What is x?
20
25
30
10
15
10
We know the angles in a triangle must add up to 180, so we can solve for x.
3x + 4x + 10 + 8x + 20 = 180
15x + 30 = 180
15x = 150
x = 10
Example Question #2 : How To Find An Angle In An Acute / Obtuse Triangle
In triangle ABC, AB=6, AC=3, and BC=4.
Quantity A Quantity B
angle C the sum of angle A and angle B
Quantity A and B are equal
Quantity A is greater
Quantity B is greater
The relationship cannot be determined from the information given.
Quantity A is greater
The given triangle is obtuse. Thus, angle is greater than 90 degrees. A triangle has a sum of 180 degrees, so angle + angle + angle = 180. Since angle C is greater than 90 then angle + angle must be less than 90 and it follows that Quantity A is greater.
Example Question #3 : How To Find An Angle In An Acute / Obtuse Triangle
In the figure above, what is the value of angle x?
To find the top inner angle, recognize that a straight line contains 180o; thus we can subtract 180 – 115 = 65o. Since we are given the other interior angle of 30 degrees, we can add the two we know: 65 + 30 = 95o.
180 - 95 = 85