Answer:
Option C. 9
Step-by-step explanation:
The question is as following:
In triangle ABC, D is the midpoint of line AB and E is the midpoint of line BC. If AC= 3x-15 and DE= 6, what is the value of x?
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See the attached figure which represents the problem.
As shown:
D is the midpoint of line AB ⇒ AD = DB
E is the midpoint of line BC ⇒ BE = EC
Apply The Mid-segment theorem which states that the mid-segment connecting the midpoints of two sides of a triangle is parallel to the third side of the triangle, and the length of this mid-segment is half the length of the third side.
So, DE = 0.5 AC
Given: Ac = 3x-15 and DE =6
∴ 6 = 0.5 (3x - 15)
solve for x
Multiply both sides by 2
12 = 3x - 15
3x = 12 + 15 = 27
x = 27/3 = 9
So, the value of x is 9
The answer is option C. 9
