If this is a

…this is a

lso a

r

ight angle.

finding missing angles

Right angles often come in pairs

A right angle is a quarter turn, so two right angles add up to one

half turn—a 180º on your skateboard, assuming you land fakey

(facing the opposite way to when you started).

Slide rail

90º turn

90º turn

Skateboard

Although it doesn’t look like one, a

straight line is still an angle—exactly a

Two right

angles sit

T

he angle on a s

traight

line is a half-turn.

180º

half turn, or two quarter turns.

together on a

straight line.

r

ight angle…

you are here 4 11

Find the next mystery angle here…

BULLET

PA

TH

MICKY

BENNY

FOOTPRINTS

18º

CRIME SCENE SKETCH

CASE GEO180

(ANGLES AS MEASURED

BUT DRAWING NOT TO

SCALE)

81º

86º

72º

?º

PLAN VIEW

BULLET

PA

TH

sharpen solution

Find the next mystery angle here…

So the total angle made by these two

angles must also be a right angle.

? + 81º = 90º

? = 9º

MICKY

BENNY

FOOTPRINTS

18º

CRIME SCENE SKETCH

CASE GEO180

(ANGLES AS MEASURED

BUT DRAWING NOT TO

SCALE)

81º

86º

72º

?º

PLAN VIEW

81º

?º

Often drawing a mini-sketch of

just the part you’re working out

makes things much clearer.

This is a right angle.

12 Chapter 1

finding missing angles

Great. Whatever. But what on earth

has working out the angle behind the

corner of the building got to do with

proving that Benny shot Micky all the

way over on the other side?

Often you need to solve the puzzle piece

by piece.

Each individual angle on the sketch doesn’t tell you

much, but together they make up an accurate picture

that shows you how every part fits in relation to the other

parts.

It would be great to jump straight to the most important

angle—if you even knew what that was—but usually we

need to find a bunch of less exciting stuff to help us get

there.

It’s like any other puzzle solving really—you’re not

always fighting the end-of-level boss, sometimes you’re

just collecting the power-ups you need to beat him/her/

it when you get there!

you are here 4 13

Y

ou can assume tha

t

a

ll the lines shown

81º

9º

bº

aº

We know that you can always fit a pair of right angles on a

straight line, but what if we don’t have right angles?

What might this pair of mystery angles (a and b) from our

crime scene sketch add up to?

her

e ar

e s

traight.

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