Angles And Rays

Explanation
A protractor is a tool specifically designed to measure angles. It consists of a semicircular or circular shape with markings that allow for precise measurement of angles. Compasses are used for drawing circles, while rulers are used for measuring straight lengths. Therefore, a protractor is the correct instrument for measuring angles.

Explanation
An angle whose measure is between 90 degrees and 180 degrees is an obtuse angle. This is because an obtuse angle is any angle that is greater than 90 degrees but less than 180 degrees. It is larger than a right angle (90 degrees) but smaller than a straight angle (180 degrees).

Explanation
HFR and HFL in the drawing are adjacent angles because they share a common side and vertex. Adjacent angles are two angles that have a common vertex and a common side between them, but do not overlap. In this case, HFR and HFL are next to each other and share the same vertex, making them adjacent angles.

Explanation
The vertex of

Explanation
A ray is a part of a line that starts at a particular point (the vertex) and extends infinitely in one direction. In the context of an angle, each side of the angle can be considered a ray because it starts at the vertex of the angle and extends indefinitely in one direction. Therefore, the correct answer is ray.

Explanation
An angle with a measure of 90 degrees is called a right angle because it forms a perfect L shape, resembling the right angle symbol. In a right angle, one side is perpendicular to the other, creating a 90-degree angle.

Explanation
The correct answer is "interior" because in geometry, the term "interior" refers to the space inside a shape or angle. In this case, point H is located within the angle LFR, making it the interior point of that angle.

Explanation
The intersection of the two sides of an angle is called its vertex. The vertex is the common endpoint of the two rays that form the angle. It is the point where the angle opens up or where the angle is formed. The vertex is an important component in defining and measuring angles.

Explanation
An angle with a measure of 180 degrees is called a straight angle because it forms a straight line. In a straight angle, the two rays are opposite to each other and lie on the same line, creating a straight line. The measure of a straight angle is always 180 degrees, making it the correct answer in this case.

Explanation
The basic unit in which angles are measured is the degree. Degrees are used to measure the size or amount of rotation in an angle. It is a standard unit of measurement in geometry and trigonometry. An angle of 360 degrees represents a complete rotation, while smaller angles are measured as fractions or multiples of a degree. The other options, "obtuse" and "adjacent," are not units of measurement but rather describe types of angles or relationships between angles.

Explanation
When two rays have the same endpoint, they form an angle. An angle is a geometric figure formed by two rays that share a common endpoint called the vertex. The rays are called the sides of the angle. Therefore, the correct answer is angle.

Explanation
Lines that cross at right angles are called perpendicular lines. Perpendicular lines intersect at a 90-degree angle, forming four right angles at the point of intersection. This is a fundamental concept in geometry and is used to describe the relationship between two lines that meet at a right angle. Straight lines are lines that extend indefinitely in both directions, while a ray is a line that starts at a point and extends infinitely in one direction.

Explanation
When two angles have the same measure, they are called congruent angles. Congruent angles have the same degree of rotation and are equal in size. The term "congruent" is used to describe geometric figures or objects that have the same shape and size. In this context, it is used to describe angles that have the same measure.

Explanation
An angle whose measure is between 0 degrees and 90 degrees is considered acute. Acute angles are less than 90 degrees and have a sharp or narrow shape. They are smaller than a right angle (90 degrees) and obtuse angle (greater than 90 degrees).

Explanation
RFH and XFE are congruent because they are vertical angles. Vertical angles are formed when two lines intersect. In this case, RFH and XFE are formed by the intersection of line RF and line XE. Vertical angles have equal measures, so RFH and XFE are congruent.

Explanation
Point R is in the exterior of