Bearings & elevation
Practice Flashcards
What is an angle of elevation?
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All Flashcards in Topic 3.3
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3.3.18 cards
What is an angle of elevation?
The angle measured upward from the horizontal to a point above you.
What is an angle of depression?
The angle measured downward from the horizontal to a point below you.
Elevation/depression are measured from what?
The horizontal — never the vertical.
How does depression relate to elevation?
The depression angle down to an object equals the elevation angle from the object back up (alternate angles).
Which ratio is most common in these problems?
tan θ = height/horizontal distance (height opposite, distance adjacent).
Tower height from 50 m away, elevation 30°?
h = 50 tan 30° ≈ 28.9 m.
What if the angle is from a person's eye?
Add the eye height to the triangle's height for the true total.
Two observers and an object form a non-right triangle — what do you use?
The sine or cosine rule.
3.3.28 cards
How is a three-figure bearing measured?
Clockwise from North, written with three digits (e.g. 045°, 250°).
Bearings of E, S, W?
East 090°, South 180°, West 270° (North is 000°/360°).
How do you write a small bearing like 7°?
With three digits: 007°.
What is a back bearing?
The reverse direction — add 180° (if under 180°) or subtract 180° (if 180° or more).
Back bearing of 070°?
070° + 180° = 250°.
Convert 'South-East' to a bearing.
135° (halfway between S 180° and E 090°, clockwise from N).
How do you solve a two-leg journey problem?
Find the interior angle at the turn, then use the cosine rule (two legs + included angle).
Why isn't the triangle angle just the difference of bearings?
You must use the North lines at the turning point — the interior angle usually involves a 180° relationship.
Topic 3.3 study notes
Full notes & explanations for Bearings & elevation
Math AA SL exam skills
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