Answer:
b = 7√3
Explanation:
This 30°- 60°- 90° triangle has the proportions:
side opposite of the 30° angle = x
side opposite of the 60° angle = x√3
side opposite of the 90° angle = 2x
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Given the side opposite of the 30° angle which is 7 units long, this can be thought of as x. Knowing the proportions of the other sides, we can find b knowing that this is the side opposite of the 60° angle which is x√3.
Since x = 7, x√3 = 7√3, and therefore
b = 7√3.