All Intermediate Geometry Resources
Example Questions
Example Question #551 : Intermediate Geometry
Two of the exterior angles of a triangle, taken at different vertices, measure and . Is the triangle acute, right, or obtuse?
Acute
Obtuse
Right
Right
At a given vertex, an exterior angle and an interior angle of a triangle form a linear pair, making them supplementary - that is, their measures total . The measures of two interior angles can be calculated by subtracting the exterior angle measures from :
The triangle has two interior angles of measures and . The sum of these measures is , thereby making them complementary. A triangle with two complementary acute angles is a right triangle.
Example Question #552 : Intermediate Geometry
True or false: It is possible for a triangle to have angles of measure , , and .
False
True
True
The sum of the measures of the angles of a triangle is . The sum of the three given angle measures is
.
This makes the triangle possible.
Example Question #23 : How To Find An Angle In An Acute / Obtuse Triangle
True or false: It is possible for a triangle to have three interior angles, each of whose measures are .
True
False
False
A triangle with three congruent angles is an equiangular - and equilateral - triangle; such an angle must have three angles that measure .
Example Question #111 : Triangles
Given: with perimeter 40;
True or false:
True
False
True
The perimeter of is the sum of the lengths of its sides - that is,
The perimeter is 40, so set , and solve for :
Subtract 26 from both sides:
, so by the Isosceles Triangle Theorem, their opposite angles are congruent - that is,
.
Example Question #51 : Acute / Obtuse Triangles
is an equilateral triangle; is the midpoint of ; the segment is constructed.
True or false: .
True
False
False
The referenced triangle is below:
In an equilateral triangle, the median from - the segment from to , the midpoint of the opposite side - is also the bisector of the angle , so
Each interior angle of an equilateral triangle, including , measures , so substitute and evaluate:
.
Example Question #26 : How To Find An Angle In An Acute / Obtuse Triangle
is an equilateral triangle. Locate a point along and construct . .
Evaluate .
The referenced figure is below. Note that , as is the case with all of the interior angles of an equilateral triangle.
The interior angles of an equilateral triangle each measure . An exterior angle of a triangle has as its degree measure the sum of its remote interior angles; specifically,
Substitute the known angle measures, and solve: