Answer:
13
Step-by-step explanation:
The vector GH has horizontal and vertical components of 5 and 12. You recognize that these are part of the Pythagorean triple (5, 12, 13), so the length of GH will be 13.
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In case you haven't run across this fun fact often enough to remember it, you can compute the length from the distance formula:
d = √((x2-x1)² +(y2-y1)²) = √((-1-4)² +(10-(-2))²) = √((-5)² +12²)
d = √(25+144) = √169 = 13
