Look at the vectors from one point to the other. From (2,5,6) to (12,25,37) is the vector [10,20,31].
From (2,5,6) to (27,55,81) is the vector [25,50,75]. Notice that [25,50,75]=25[1,2,3] and [10,20,31]=10[1,2,3.1].

Close to being collinear, but not quite.

Problem 7

When the line intersects the xz=plane, y=0.

Substitute this value of r to find the coordinates.

## Table of Contents

## Page 47

## Problem 1

## Problem 2 and 3

should be 36.87 degrees

## Problem 4

## Problem 5

## Problem 6

Look at the vectors from one point to the other. From (2,5,6) to (12,25,37) is the vector [10,20,31].

From (2,5,6) to (27,55,81) is the vector [25,50,75]. Notice that [25,50,75]=25[1,2,3] and [10,20,31]=10[1,2,3.1].

Close to being collinear, but not quite.

## Problem 7

When the line intersects the xz=plane, y=0.

Substitute this value of r to find the coordinates.

## Problem 8

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## Problem 9

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## Problem 10

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## Problem 11

## Problem 12

## Page 48

## Problem 1

## Problem 2

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## Problem 3

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## Problem 4

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## Problem 5

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## Problem 6 and 7

## Problem 8

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## Problem 9

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## Problem 10

## Problem 11

## Problem 12

You need to develop a systematic counting strategy.

I think there are 35, and

NONEare scalene## Problem 13

## Problem 14

It would be a great exercise to construct a drag-testable model similar to the one that I created.