To find how many blocks Joel would ride in total when biking back to his starting point, we first determine the distance he traveled to his starting point.
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Distance Joel biked away from his starting point:
- He biked 9 blocks East.
- He also biked 12 blocks North.
We can visualize his journey as a right triangle where:
- The horizontal leg (East) is 9 blocks.
- The vertical leg (North) is 12 blocks.
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Using the Pythagorean theorem: To find the direct distance (the hypotenuse) back to his starting point, we can use the Pythagorean theorem:
\[ c = \sqrt{a^2 + b^2} \]
Here, \( a = 9 \) blocks (East) and \( b = 12 \) blocks (North).
\[ c = \sqrt{9^2 + 12^2} = \sqrt{81 + 144} = \sqrt{225} = 15 \]
So, the direct distance back to his starting point is 15 blocks.
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Total distance he rode:
- Distance away from the starting point = 9 blocks (East) + 12 blocks (North) = 21 blocks.
- Distance back to the starting point = 15 blocks.
Therefore, the total distance he rode:
\[ \text{Total distance} = 21 \text{ blocks (out)} + 15 \text{ blocks (back)} = 36 \text{ blocks}. \]
So, the total number of blocks Joel would ride all together is 36 blocks.