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Head First 2D Geometry
book

Head First 2D Geometry

by Stray (Lindsey Fallow), Dawn Griffiths
November 2009
Beginner content levelBeginner
368 pages
8h 55m
English
O'Reilly Media, Inc.
Content preview from Head First 2D Geometry
140 Chapter 3
how much rope?
A longer rope swings further and lower
The wider the gap between the platforms, the more exciting the swing
will be—but there’s a catch. The TV company doesn’t just want the
widest swing, they want the widest possible swing without people
smashing into the floor!
Safety line
The floor
4m
2m
The rope is fixed to a
point in the ceiling here.
Competitor
starts here.
In the middle of the
swing the competitor
is closest to the
floor.
This is the lowest
safe height for
the end of the
rope—the height
a very tall person
needs when
swinging.
2m
you are here 4 141
the pythagorean theorem
So, before we can work out
anything else, we need to
quickly find how long the
rope can safely be, right?
What’s the longest the rope can be without going below the safety line?
Q:
The Pythagorean Theorem formula (c
2
= a
2
+ b
2
) looks
like it’s for finding the hypotenuse (c). But sometimes we’re
finding a length of a short side. How do I know what I’m
supposed to be finding and how to find it?
A: You can rearrange the formula to focus on one of the short
sides (legs). Like a
2
= c
2
– b
2
or b
2
= c
2
– a
2
, but the most reliable
thing to do is to focus on the meaning behind the pattern. If you’re
looking for the hypotenuse remember that the squares of the two
shortest sides add up to make the square ...
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Publisher Resources

ISBN: 9780596808365Errata Page