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# Angles and Lines

Forgive us for being obtuse, but this is a cute concept, and we think it’s right for you.

# Types of Angles

How many acute angles does an obtuse triangle have?

In the above diagram, $$A,$$ $$B,$$ and $$C$$ lie on a straight line. If $$\color{Blue}{ \angle ACD ={151}^\circ},$$ which of the following is true of $$\color{Red} { \angle BCD}$$?

Angles $$ABC$$ and $$CBD$$ are adjacent with common vertex $$B$$ and common edge $$\overline{BC}.$$ If $$\angle ABC={51}^\circ$$ and $$\angle CBD={40}^\circ,$$ which of the following is true of $$\angle ABD?$$

If $$\angle A$$ is an acute angle, $$\angle B$$ is a right angle and $$\angle C$$ is an obtuse angle, which of the following is true of $$\angle A+\angle B+\angle C ?$$

In the above diagram, $$A$$, $$B$$, and $$C$$ lie on a straight line. Which of the following is true of angle $$\angle BAC$$?

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