i need help with all triangles (1 Viewer)

[elly-mae]

hey im new to this but i was just wondering if any one has some easy ways to remember the diffrent ways of working out the triangle questions
i know how to do them i just have trouble finding out which one is which and what to do with it
all help would be appreciated
thank you

 

[PC]

Which triangle questions?

 

[elly-mae]

a sky diver in an air craft, flying at a height of 6000m at a speed of 140m/s, observes her target ahead at an angle of depression of 36 27'

1)calculate the horizontal distance from the air craft's current location to the point directly abouve the target. answer correct to the nearest metre

2)how long will the air craft take to reach the point directly above the target. correct to the nearest second

thank you

 

[PC]

Draw a diagram. You'll have a plane, with a vertical distance of 6000 m and then a diagonal line from the plane down to the target. The angle at the target between the ground and the diagonal line is 36°27' (this isn't the angle of depression, but it's they're alternate angles).

(1) You want the horizontal distance. That's the distance from under the plane across to the target. So:
tan 36°27' = 6000/d
d = 6000/tan 36°27'
d = 8123.3508
d = 8123 m

(2) You've just worked out the distance that the plane has to travel, and you're given the speed. We need time, so remember the distance-speed-time rule.
T = D/S
= 8123/140
= 58.02142857
= 58 seconds

Hope that helps

 

[elly-mae]

yes very much so. thank you

 

[DownInFlames]

drawing pictures is really helpful for trig. If in doubt, always draw a picture, then run through all the different rules to see which ones you need to use.

 

[Sam(uel)]

Something to note is that if you had trouble and simply couldn't figure out how to do (1), i've been told that even if you don't have the answer to use for (2) you can make up a number and you'll still be given marks (idk if full) for (2) because you know how to do it ('-');

 

[DownInFlames]

(idk if full)

You get full marks for part 2 if you did it correctly based on the answer you got for part 1 (provided it doesn't make the question loads easier)