<h3>Answer:</h3><h3>There are 3 true statements, and the true statements are: </h3><h3>choice A, choice C, choice D</h3>
======================================================
Explanation:
A. True. All triangles have 3 straight sides and 3 angles.
B. False. All triangles are polygons. A polygon is just a collection of line segments glued together to form a closed shape.
C. True. A plane figure is a flat shape.
D. True. See choice A.
E. False. Some triangles do not have one right angle. Example: obtuse triangles do not have any right angles.
Answer:
First: 15
Second: 21
Third: 45
Step-by-step explanation:
In order to create the equation we need to represent the evenings with an alebraic term, in thsi case we are going to represent the second evening with an X
Second evening:x
The first night she got 6 fewer calls than the second: Second-6=x-6
The third night she received 3 times the first: 3(first night)=3(x-6)
The equation is First Night plus second night plus third night equals 81.

So the first evening he received 15 calls, the second he received 21 and the third one he received 45.
Answer:
consecutive interior angles
Step-by-step explanation:
inside of the angle and consecutive to each other
If she chose the color she would have 12 options left.
Answer:
We can determine from their equations whether two lines are parallel by comparing their slopes. If the slopes are the same and the y-intercepts are different, the lines are parallel. If the slopes are different, the lines are not parallel. Unlike parallel lines, perpendicular lines do intersect