Lesson 14
Parallel Lines and the Angles in a Triangle
Problem 1
For each triangle, find the measure of the missing angle.
Solution
Teachers with a valid work email address can click here to register or sign in for free access to Formatted Solution.
Problem 2
Is there a triangle with two right angles? Explain your reasoning.
Solution
Teachers with a valid work email address can click here to register or sign in for free access to Formatted Solution.
Problem 3
In this diagram, lines \(AB\) and \(CD\) are parallel.
Angle \(ABC\) measures \(35^\circ\) and angle \(BAC\) measures \(115^\circ\).
 What is \(m{\angle ACE}\)?
 What is \(m{\angle DCB}\)?
 What is \(m{\angle ACB}\)?
Solution
Teachers with a valid work email address can click here to register or sign in for free access to Formatted Solution.
Problem 4
Here is a diagram of triangle \(DEF\).
 Find the measures of angles \(q\), \(r\), and \(s\).
 Find the sum of the measures of angles \(q\), \(r\), and \(s\).

What do you notice about these three angles?
Solution
Teachers with a valid work email address can click here to register or sign in for free access to Formatted Solution.
Problem 5
The two figures are congruent.
 Label the points \(A’\), \(B’\) and \(C’\) that correspond to \(A\), \(B\), and \(C\) in the figure on the right.
 If segment \(AB\) measures 2 cm, how long is segment \(A’B’\)? Explain.
 The point \(D\) is shown in addition to \(A\) and \(C\). How can you find the point \(D’\) that corresponds to \(D\)? Explain your reasoning.
Solution
Teachers with a valid work email address can click here to register or sign in for free access to Formatted Solution.
(From Unit 1, Lesson 11.)