Lesson 12

Segments $AB$, $EF$, and $CD$ intersect at point $C$, and angle $ACD$ is a right angle. Find the value of $g$.

$M$ is a point on line segment $KL$. $NM$ is a line segment. Select all the equations that represent the relationship between the measures of the angles in the figure.

$a=b$

$a+b=90$

$b=90-a$

$a+b=180$

$180-a=b$

$180=b-a$

Use the diagram to find the measure of each angle.

1. $m\angle ABC$
2. $m\angle EBD$
3. $m\angle ABE$

Lines $k$ and $\ell$ are parallel, and the measure of angle $ABC$ is 19 degrees.

1. Explain why the measure of angle $ECF$ is 19 degrees. If you get stuck, consider translating line $\ell$ by moving $B$ to $C$.
2. What is the measure of angle $BCD$? Explain.

The diagram shows three lines with some marked angle measures.

Find the missing angle measures marked with question marks.

Lines $s$ and $t$ are parallel. Find the value of $x$.