Question

1. which of the following is incorrect about the properties of a right angle?

a. it is often used in constructing squares
b. it is formed by two perpendicular lines
c. it measures 90 degrees
d. it measures more than 90 degrees

1. what characteristic does a line have if its slope is zero?

a. the line is vertical
b. the line is increasing
c. the line is decreasing
d. the line is horizontal

Explanation:

For question 9, a right - angle measures 90 degrees, is formed by two perpendicular lines and is used in constructing squares. Option d is incorrect as it says a right - angle measures more than 90 degrees.
For question 10, the slope formula is $m=\frac{y_2 - y_1}{x_2 - x_1}$. When $m = 0$, $y_2=y_1$, which represents a horizontal line.

Answer:

1. d. It measures more than 90 degrees
2. d. The line is horizontal