Question:
Classify a triangle with three equal sides by its sides and its angles.
Equilateral Equiangular
Two sides measure x+3 and 11. They are congruent. Solve for x.
x=8
A right triangle has one acute angle of 35°. Find the other acute angle.
55°
100
What congruence postulate uses three pairs of sides?
Side Side Side (SSS)
If AB=CD and CD=EF, then AB=EF. What property?
Transitive Property
Question:
Classify a triangle with sides 4 cm, 4 cm, and 7 cm by its sides.
Isosceles
Triangle angles are 3x, 2x+10, and 50°. Find x
x=24
Isosceles triangle with vertex angle 58°. Find each base angle.
61°
Two right triangles with congruent hypotenuse and a leg.
HL
Angles A ≅ D, B ≅ E, and AB = DE. What congruence theorem?
AAS
A triangle has angles 40°, 60°, and 80°. Classify by angles and by sides.
Scalene and acute.
Triangle with sides 5, 5, and 2x−1. Find x if it is equilateral.
x=3
Triangle angles are in ratio 2:3:4. Find all angles.
40°, 60°, 80°
Two sides and a non-included angle (SSA). Can this prove congruence?
No, SSA is not always valid
OM bisects angle AOB. What angles are congruent?
∠AOM ≅ ∠BOM
Explain the difference between an isosceles triangle and a scalene triangle.
Isosceles has two equal sides; scalene has no equal sides.
In triangle PQR, PQ=3x-1 and PR= x+10. If PQ=PR, solve for x.
x= 5.5
Angle A = 3x, Angle C = B + 20, Angle B= x. Find all angles.
A = 96°, B = 32°, C = 52°
AB=DE, BC=EF, and <B=<E. What proves them congruent?
Side Angle Side (SAS)
Given AB = AC, prove ∠B = ∠C. What type of triangle is this?
Isosceles triangle → base angles congruent
A triangle has two congruent angles and all different side lengths. Is this possible and why?
No, congruent angles imply the opposite sides are congruent.
Triangle DEF: DE = 2x+3, DF= 4x+1. If DE = DF, find x.
x=1
Exterior angle = sum of remote interior angles (45° and 70°). Find exterior angle and its linear-pair partner.
Exterior = 115°, linear pair = 65°
If △JKL≅△MNP name three corresponding congruent parts.
JK ≅ MN, KL ≅ NP, JL ≅ MP (angles also acceptable)
Given AB = AC and ∠BAD = ∠CAD, prove BD = CD. What is the reason?
Triangles congruent by SAS