Introduction To Geometry: Lines, Angles, And Triangles

An equilateral triangle is a triangle with three congruent sides. Since the given statement describes a triangle with three congruent sides, it matches the definition of an equilateral triangle. Therefore, the correct answer is equilateral triangle.

A scalene triangle is a triangle that has no congruent sides. In other words, all three sides of a scalene triangle have different lengths. This is different from an isosceles triangle, which has at least two congruent sides, or an equilateral triangle, which has all three sides congruent. Therefore, the given answer, "Scalene triangle," is correct.

Acute angles are angles that measure less than 90 degrees. This means that the measure of the angle is smaller than a right angle (90 degrees) or a straight angle (180 degrees). Therefore, the given answer "Acute angles" correctly describes angles that measure less than 90 degrees.

Obtuse angles are angles that measure greater than 90 degrees and less than 180 degrees. These angles are larger than a right angle (which measures 90 degrees) but smaller than a straight angle (which measures 180 degrees). In other words, obtuse angles are wider than a right angle but not as wide as a straight angle.

Congruent means having the same measure or size. In the context of this question, the options "obtuse," "acute," and "concrete" do not relate to having the same measure. However, "congruent" does align with the given definition. Therefore, "congruent" is the correct answer.

Parallel lines are two lines in a plane that never intersect or cross. They have the same slope and will always remain equidistant from each other. These lines can be found in various geometrical shapes and are commonly used in mathematics and engineering.

A triangle is a geometric shape that has three sides and three angles. It is formed by three line segments that intersect only at their endpoints. The name "triangle" accurately describes this shape, making it the correct answer choice.

Right angles have a measure of 90 degrees. They are formed when two lines intersect and create a square corner. In a right angle, one side of the angle is vertical and the other is horizontal, creating a perfect L shape. Right angles are commonly found in geometric shapes such as squares and rectangles, as well as in everyday objects like corners of buildings or furniture. They are important in geometry and have various applications in fields such as architecture, engineering, and design.

A triangle is formed by three line segments that intersect only at their end points. In a triangle, each line segment connects two of the end points, forming three sides. Therefore, the given answer, "Triangle," is correct.

Supplementary angles are pairs of angles that add up to 180 degrees. This means that when you add the measures of the angles in a pair, the sum will always be equal to 180 degrees. Therefore, supplementary angles are the correct answer because they satisfy the condition mentioned in the question. Complementary angles have a sum of 90 degrees, obtuse angles are greater than 90 degrees, and right angles are exactly 90 degrees, so they do not meet the requirement of having a sum of 180 degrees.

Straight angles are angles that have measures equal to 180 degrees. A straight angle forms a straight line, and the sum of its measures is always 180 degrees. This means that a straight angle is larger than a right angle (90 degrees) and both acute and obtuse angles. Straight angles are characterized by their straightness and lack of curvature, and they divide a circle into two equal halves.

Perpendicular lines are lines that intersect at a right angle. This means that the two lines form a 90-degree angle where they meet. Unlike parallel lines, which never intersect, or transversal lines, which intersect at any angle, perpendicular lines have a specific angle of intersection. Therefore, the correct answer is perpendicular lines.

A transversal line is a line that intersects two or more other lines. It is not parallel or perpendicular to the other lines, but rather cuts across them. This type of line is commonly used in geometry to determine angles and relationships between different lines.

Adjacent angles are angles that have the same vertex, share a common side, and do not overlap. This means that the two angles are next to each other and are connected at one point. They do not overlap or intersect.

Vertical angles are formed when two lines intersect. They are opposite angles and are congruent to each other. This means that the measure of one vertical angle is equal to the measure of the other vertical angle. Therefore, the correct answer is vertical angles.

Complementary angles are pairs of angles that, when added together, equal 90 degrees. This means that the sum of their measures is equal to a right angle. Therefore, complementary angles are the correct answer because they satisfy the condition stated in the question. Straight angles have a measure of 180 degrees, right angles have a measure of 90 degrees, and supplementary angles have a sum of 180 degrees, but none of these options meet the requirement of having a sum of 90 degrees.