## 1. If two parallel lines are intersected by a transversal, then the alternate interior angles are:

### Answer:

### Explanation:

For two parallel lines cut by a transversal, the alternate interior angles are congruent or equal.

## 2. An angle that measures exactly 180 degrees is called:

### Answer:

### Explanation:

A straight angle lies on a straight line and measures 180 degrees.

## 3. Vertically opposite angles are always:

### Answer:

### Explanation:

When two lines intersect, the angles formed opposite to each other are called vertically opposite angles, and they are always equal.

## 4. The sum of angles around a point is:

### Answer:

### Explanation:

The total of all angles around a point is 360 degrees.

## 5. If two lines are perpendicular to each other, then the angle between them is:

### Answer:

### Explanation:

Two lines are said to be perpendicular if they intersect to form a right angle, which measures 90 degrees.

## 6. Which of the following angles is the smallest?

### Answer:

### Explanation:

An acute angle measures less than 90 degrees, making it the smallest among the given options.

## 7. An angle measuring more than 90 degrees but less than 180 degrees is termed as:

### Answer:

### Explanation:

An obtuse angle is greater than 90 degrees but less than 180 degrees.

## 8. If a ray stands on a line, then the sum of the two adjacent angles so formed is:

### Answer:

### Explanation:

When a ray stands on a line, it divides the line into two adjacent angles that are supplementary, meaning their sum is 180 degrees.

## 9. Two lines in a plane that never meet, irrespective of how long they are extended, are called:

### Answer:

### Explanation:

Parallel lines are two or more lines that run in the same direction and never meet, no matter how far they are extended.

## 10. Which of the following pairs of angles are always supplementary?

### Answer:

### Explanation:

A linear pair is a pair of adjacent angles whose non-common sides are opposite rays. They always sum up to 180 degrees, making them supplementary.

## 11. The sum of all interior angles of a triangle is:

### Answer:

### Explanation:

The total of all interior angles in any triangle is always 180 degrees.

## 12. If two lines are cut by a transversal such that a pair of alternate exterior angles are equal, then the lines are:

### Answer:

### Explanation:

Equal alternate exterior angles are a condition for two lines to be parallel when cut by a transversal.

## 13. Which of the following statements is always true?

### Answer:

### Explanation:

A right angle always measures 90 degrees, so all right angles are equal.

## 14. The angles that have a common vertex and a common side but no common interior points are called:

### Answer:

### Explanation:

Adjacent angles share a common vertex and side but don't have any interior points in common.

## 15. When two lines intersect, the angles formed opposite to each other are called:

### Answer:

### Explanation:

When two lines intersect, they form pairs of equal angles opposite to each other, called vertically opposite angles.

## 16. The angles which sum up to 90 degrees are:

### Answer:

### Explanation:

Two angles are complementary if the sum of their measures is 90 degrees.

## 17. Two lines that intersect to form right angles are:

### Answer:

### Explanation:

Two lines that intersect to form right angles (90 degrees) are perpendicular to each other.

## 18. The angle which is equal to its complementary angle is:

### Answer:

### Explanation:

If an angle and its complementary angle are equal, then each angle is 45 degrees because their sum is 90 degrees.

## 19. If one of the angles in a linear pair is acute, then the other angle is:

### Answer:

### Explanation:

In a linear pair, if one angle is acute (less than 90 degrees), then the other must be obtuse because their sum is 180 degrees.

## 20. An angle whose measure is greater than 180 degrees but less than 360 degrees is:

### Answer:

### Explanation:

A reflex angle measures more than 180 degrees but less than 360 degrees.