All Intermediate Geometry Resources
Example Questions
Example Question #121 : Acute / Obtuse Triangles
Using the triangle shown above, find possible measurements for the corresponding sides of a similar triangle?
and
and
and
and
and
Since the two triangles are similar, each triangles three corresponding sides must have the same ratio.
The ratio of the triangle is:
Applying this ratio we are able to find the lengths of a similar triangle.
Example Question #181 : Triangles
Given: and .
True or false: It follows from the given information that .
False
True
True
As we are establishing whether or not , then , , and correspond respectively to , , and .
According to the Side-Angle-Side Similarity Theorem (SASS), if the lengths of two pairs of corresponding sides of two triangles are in proportion, and their included angles are congruent, then the triangles are similar.
and are corresponding sides, as are and ; and are their included angles. Substituting
Therefore, , and corresponding sides are in proportion.
and ; the included angles are congruent.
The conditions of SASS are met, and it follows that .
Example Question #631 : Intermediate Geometry
Given: and .
True or false: From the above six statements, it follows that .
False
True
False
As we are establishing whether or not , then , , and correspond respectively to , , and .
If , then corresponding sides must be in proportion; that is, it must hold that
Substituting the lengths of the sides for the respective quantities:
The inequality of these two side ratios disproves the similarity of the triangles, so the correct answer is "false".
Example Question #131 : Acute / Obtuse Triangles
Given: and .
True or false: From the above four statements, it follows that .
True
False
True
As we are establishing whether or not , then , , and correspond respectively to , , and .
The sum of the measures of the interior angles of a triangle is . Therefore,
Set and , and solve for :
By the Angle-Angle Similarity Postulate (AA), two triangles are similar if two angles of the first triangle are congruent to those of their counterparts in the second. and , so ; and , so . The conditions of AA are met, so it follows that . The correct response is "true".
Example Question #132 : Acute / Obtuse Triangles
Given: and .
True or false: From the above three statements, it follows that .
True
False
True
As we are establishing whether or not , then , , and correspond respectively to , , and .
Let .
Let
The measures of the interior angles of a triangle total . Therefore,
Substituting:
By the same reasoning,
Therefore, .
By the Angle-Angle Similarity Postulate (AA), two triangles are similar if two angles of the first triangle are congruent to those of their counterparts in the second. and , so the conditions of AA are met; it follows that .
Example Question #16 : How To Find If Two Acute / Obtuse Triangles Are Similar
Given: , with Point on and Point on .
True or false: From the given information, it follows that .
False
True
False
As we are establishing whether or not , then , , and correspond respectively to , , and .
If two triangles are similar, then it must hold that corresponding sides are in proportion. Specifically, if , it must hold that
By the Segment Addition Postulate,
and
Set , , , in the above proportion statement, which becomes
Reduce both ratios to lowest terms:
The corresponding sides are not proportional, so the statement is false.
Example Question #133 : Acute / Obtuse Triangles
Given: , with Point on and Point on .
True or false: From the given information, it follows that .
True
False
True
As we are establishing whether or not , then , , and correspond respectively to , , and .
By the Side-Angle-Side Similarity Theorem (SASS), two triangles are similar if two pairs of corresponding sides are in proportion and their included angles are congruent.
Examine two pairs of corresponding sides: and , and and . In both cases, their included angle is ; by the Reflexive Property of Congruence, .
It remains to be demonstrated that
By the Segment Addition Postulate,
and
Set , , , in the above proportion statement, which becomes
Reduce both ratios to lowest terms:
The corresponding sides are proportional.
The conditions of SASS have been proved, so the statement is true.
Example Question #631 : Plane Geometry
Given: and such that
Which statement(s) must be true?
(a)
(b)
(b) but not (a)
Neither (a) nor (b)
(a) but not (b)
(a) and (b)
(a) but not (b)
The two given angle congruences set up the conditions of the Angle-Angle Similarity Postulate - if two angles of one triangle are congruent to the two corresponding angles of another triangle, the two triangles are similar. It follows that
.
However, congruence cannot be proved, since at least one side congruence is needed to prove this. This is not given in the problem.
Therefore, statement (a) must hold, but not necessarily statement (b).
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