1.
This type of triangle has one 90 degree angle.
Correct Answer
B. Right
Explanation
A triangle with one 90 degree angle is called a right triangle. In a right triangle, one of the angles measures exactly 90 degrees, making it the largest angle in the triangle. The other two angles in a right triangle are acute angles, meaning they are less than 90 degrees. Therefore, the correct answer is right.
2.
A ________ triangle is one where all 3 angles measure less than 90 degrees.
Correct Answer
A. Acute
Explanation
An acute triangle is a triangle where all three angles measure less than 90 degrees. This means that none of the angles in the triangle are right angles (90 degrees) or obtuse angles (greater than 90 degrees).
3.
A triangle where all sides are congruent is called
Correct Answer
C. Equilateral
Explanation
An equilateral triangle is a triangle where all sides are congruent. This means that all three sides of the triangle have the same length. In contrast, a scalene triangle has no congruent sides, and an isosceles triangle has two congruent sides. Therefore, the correct answer is equilateral.
4.
An isosceles triangle has
Correct Answer
B. 2 congruent sides
Explanation
An isosceles triangle is a triangle with two sides of equal length. The term "isosceles" means "equal legs," referring to the two congruent sides of the triangle. The third side, called the base, may have a different length.
5.
All 3 interior angles of a triangle add up to
Correct Answer
B. 180 degrees
Explanation
The correct answer is 180 degrees because the sum of the interior angles of any triangle is always equal to 180 degrees. This is a fundamental property of triangles in Euclidean geometry. No matter the size or shape of the triangle, the sum of its three interior angles will always be 180 degrees.
6.
A triangle with no congruent sides and 1 angle greater than 90 degrees would be called __________ _________
Correct Answer
A. Obtuse scalene
Explanation
A triangle with no congruent sides is called a scalene triangle. Additionally, a triangle with one angle greater than 90 degrees is known as an obtuse triangle. Therefore, a triangle that has no congruent sides and one angle greater than 90 degrees is classified as an obtuse scalene triangle. This type of triangle has all sides of different lengths (scalene) and one angle that is greater than 90 degrees (obtuse).
7.
In a triangle, the lengths of the sides are 7 cm, 24 cm, and 25 cm. Which of the following statements is true?
Correct Answer
C. The triangle is right-angled
Explanation
To check if the triangle is right-angled, use the Pythagorean theorem:
7^2+24^2=49+576=625=25^2
Since the sides satisfy the Pythagorean theorem, the triangle is right-angled.
8.
In triangle ABC, AB=13 cm, BC=14 cm, and CA=15 cm. Which of the following is the correct measure of angle C?
Correct Answer
B. 75.5°
Explanation
To find angle C, use the Law of Cosines:
c^2=a^2+b^2−2ab⋅cosC
Substituting a=13, b=14 cm, and c=15 cm:
15^2=13^2+14^2−2×13×14×cosC
225=169+196−364×cosC
225=365−364×cosC
CosC=140/364=0.3846
Thus, C≈cos−1(0.3846)≈75.5°C
9.
In a right triangle, what is the name of the side opposite the right angle?
Correct Answer
C. Hypotenuse
Explanation
In a right triangle, the side opposite the right angle (90 degrees) is known as the hypotenuse. This is the longest side of the triangle because, according to the Pythagorean theorem, the square of the hypotenuse’s length is equal to the sum of the squares of the other two sides. This theorem is a fundamental principle in trigonometry and is used extensively in various fields of science and engineering.
10.
What do you call a triangle that has two equal sides?
Correct Answer
B. Isosceles triangle
Explanation
An isosceles triangle is characterized by having two sides of equal length, which are called the legs. The angles opposite these equal sides are also equal. This symmetry gives the isosceles triangle its distinctive properties, such as equal altitudes and medians from the equal angles. Isosceles triangles are commonly used in architecture and design because of their symmetrical properties.