If B is the midpoint of AC and AC = 8x - 20, find BC.
Understand the Problem
The question is asking us to find the length of segment BC given that B is the midpoint of AC. We need to use the information that AC equals 8x - 20 to find the value of x and subsequently calculate BC.
Answer
The length of segment \( BC \) is \( 26 \).
Answer for screen readers
The length of segment ( BC ) is ( 26 ).
Steps to Solve
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Determine the Length of AC Given that segment ( AC = 8x - 20 ), this represents the total length of the segment between points A and C.
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Use B as the Midpoint Since ( B ) is the midpoint of ( AC ), it means that ( AB = BC ). Therefore, we can express the length of ( BC ) as half of ( AC ):
$$ BC = \frac{AC}{2} $$
- Substitute for AC Substituting the expression we have for ( AC ):
$$ BC = \frac{8x - 20}{2} $$
- Simplify the Expression Now, simplify the expression for ( BC ):
$$ BC = 4x - 10 $$
- Set Up the Equation Using ( AB ) We also know that ( AB = 3x - 1 ) (as indicated in the figure). Since ( AB = BC ), we can set the equations equal to each other:
$$ 3x - 1 = 4x - 10 $$
- Solve for x Now, solve the equation for ( x ):
- Rearranging gives us:
$$ 10 - 1 = 4x - 3x $$
$$ 9 = x $$
- Calculate the Value of BC Substituting ( x = 9 ) back into the equation for ( BC ):
$$ BC = 4(9) - 10 $$
$$ BC = 36 - 10 $$
$$ BC = 26 $$
The length of segment ( BC ) is ( 26 ).
More Information
Since ( B ) is the midpoint, both segments ( AB ) and ( BC ) are equal. This allows us to set up the equation easily. Knowing ( AB ) is twice the size of ( BC ) simplifies the calculation.
Tips
- Forgetting that the midpoint divides the segment into two equal parts can lead to incorrect calculations.
- Incorrectly simplifying the expressions when solving for ( x ) can result in wrong values.
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