All Common Core: High School - Geometry Resources
Example Questions
Example Question #5 : Prove Theorems About Triangles.
True or False: The Base Angles Converse states that if two base angles are congruent, then their opposite sides are congruent.
False
True
True
Since the Base Angles Theorem states that if two adjacent sides are congruent then their opposite angles are congruent, then its converse assumes that the two base angles are congruent and then their opposite sides are congruent.
Example Question #3 : Prove Theorems About Triangles.
Consider the following theorem: If two triangles have two pairs of congruent corresponding sides and their included angle is congruent, then these two triangles are congruent. When proving this theorem, what information do we assume to begin the proof?
Assume that two triangles have two pairs of corresponding congruent sides
Assume that the two triangles are congruent
Assume that two triangles have a pair of corresponding congruent angles
Assume that two triangles have two pairs of corresponding congruent sides and their included angle is congruent
Assume that two triangles have two pairs of corresponding congruent sides and their included angle is congruent
When theorems are presented to you in an “if-then” format, you always assume the entire “if” part. This allows you to construct an argument that you will be able to prove to be true using the given information.
Example Question #7 : Prove Theorems About Triangles.
Fill in the blanks below to complete the proof for the HL Theorem. Use the figure below to find the given information.
perpendicular, altitude,
altitude, perpendicular,
angle bisector, bisector,
altitude, perpendicular,
Follow the detailed proof below.
Example Question #8 : Prove Theorems About Triangles.
The triangle inequality theorem states that if you have a triangle then
Fill in the blanks for the proof of the theorem below using triangle
To begin this proof we first must let there exist the triangle , where the length of and is a shared side between the two triangles.
obtuse triangle,
isosceles triangle,
equilateral triangle,
isosceles triangle,
Follow the detailed proof below for an explanation.
To begin this proof we first must let there exist the triangle , where the length of and is a shared side between the two triangles.
Example Question #3 : Prove Theorems About Triangles.
Fill in the blanks to the proof below. We are proving that the base angles of isosceles triangles, , are congruent. This is a proof of the isosceles triangle theorem.
, similar, angle bisector, SAS
, congruent, midpoint, ASA
, congruent, angle bisector, SAS
, congruent, angle bisector, SAS
Example Question #10 : Prove Theorems About Triangles.
Prove that if one side of a triangle is longer than another side of the same triangle, then the angle opposite the longer side will be greater than the angle opposite the shorter side. Use the information that for triangle .
Proof:
Proof:
Proof:
Proof:
Follow the detailed proof below.
Example Question #1 : Understand That By Similarity, Side Ratios In Right Triangles Are Properties Of The Angles In The Triangle, Leading To Definitions Of Trigonometric Ratios For Acute Angles
Using the sides of a right triangle, what is the definition of ?
We can see this to be true by looking at the following triangle.
We are considering . The opposite side to is . has two adjacent sides, but since is opposite to the right angle, this is the hypotenuse of the triangle. So the adjacent side to must be . We can set up the following equation to check and make sure that .
This shows that .
Example Question #1 : Understand That By Similarity, Side Ratios In Right Triangles Are Properties Of The Angles In The Triangle, Leading To Definitions Of Trigonometric Ratios For Acute Angles
True or False: By similarity, side ratios in right triangles are properties of the angles in the triangle.
False
True
True
Similar right triangles are two right triangles that differ in side lengths but have congruent corresponding angles. This means that if you have an angle, , in the first triangle and an angle, , in the second triangle. So .If we are considering the cosine of these two angles.
Side ratios would also follow from computing the sine and tangent of the angles using their sides as well. This shows that the side ratios are properties of the angles in the triangles.
Example Question #3 : Understand That By Similarity, Side Ratios In Right Triangles Are Properties Of The Angles In The Triangle, Leading To Definitions Of Trigonometric Ratios For Acute Angles
Assume the two triangles below are similar. Using the fact that their sides ratios are , what trigonometric function could this represent for angles and
,
,
,
,
,
We must begin by manipulating our equation of the side ratios to get fractions that include both of the sides of the same triangles:
multiply both sides by
divide both sides by
If we look at angle we see that is the . Looking at angle we see that is also . This is the definition of the cosine function of an angle. So:
Example Question #4 : Understand That By Similarity, Side Ratios In Right Triangles Are Properties Of The Angles In The Triangle, Leading To Definitions Of Trigonometric Ratios For Acute Angles
Consider the following right triangle. Use trigonometric ratios to solve for and .
We are given angle and we need to find sides and . So first we need to think about what relation these sides are to angle . Side is the hypotenuse of the triangle since it is the opposite of the right angle. Side is opposite angle . Recall that the trigonometric ratio that corresponds to sine is . We can solve for the missing sides by solving for the following equation.
It follows that: