Unit 7, Lesson 9
Drawing Triangles (Part 1)
Grade 7
9.1
Warm-up
Which three go together? Why do they go together?
Student Lesson Summary
Sometimes, we are given two different angle measures and a side length, and it is impossible to draw a triangle. For example, there is no triangle with side length 2 and angle measures and :
In the figure a horizontal line segment is drawn and labeled 2. On the left end of the line segment, a dashed line is drawn upward and to the left. The angle formed between the dashed line and the horizontal line is labeled 120 degrees. On the right end of the horizontal line, a dashed line is drawn upward and to the right. The angle formed between the dashed line and horizontal line is labeled 100 degrees.
Sometimes, we are given two different angle measures and a side length between them, and we can draw a unique triangle. For example, if we draw a triangle with a side length of 4 between angles and , there is only one way in which they can meet up and make a triangle:
Any triangle drawn with these three conditions will be identical to the one above, with the same side lengths and the same angle measures.
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