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Example Questions
Example Question #41 : Acute / Obtuse Triangles
is an equilateral triangle. Points are the midpoints of , respectively. is constructed.
All of the following are true except:
Each side of is parallel to a side of .
All of the statements in the other four choices are correct.
The perimeter of is twice that of .
The area of is twice that of .
The area of is twice that of .
The three sides of are the midsegments of , so is similar to .
By the Triangle Midsegment Theorem, each is parallel to one side of .
By the same theorem, each has length exactly half of that side, giving twice the perimeter of .
But since the sides of have twice the length of those of , the area of , which varies directly as the square of a sidelength, must be four times that of .
The correct choice is the one that asserts that the area of is twice that of .
Example Question #2 : Calculating If Two Acute / Obtuse Triangles Are Similar
.
Order the angles of from least to greatest measure.
The angles of cannot be ordered from the information given.
In a triangle, the angle of greatest measure is opposite the side of greatest measure, and the angle of least measure is opposite the side of least measure. , so their opposite angles are ranked in this order - that is, .
Corresponding angles of similar triangles are congruent, so, since , .
Therefore, by substitution, .
Example Question #1 : Calculating If Two Acute / Obtuse Triangles Are Similar
The triangles are similar. What is the value of x?
The proportions of corresponding sides of similar triangles must be equal. Therefore, . .