trigonometry help (1 Viewer)

[anita_wax]

ok im up to trigonometry in my afternoon study, and im really rusty on this.
ive browsed all my notes and some others from bos and i can't find any thing to help me with the 1st,5th q so far (only up to 5)
(my big dilemma for q5 is ive forgotten how to convert the decimal into the angle, it's not even shown in the textbook how to do that)

http://hsc.csu.edu.au/maths/general/hsc/measurement/m6/m6_mc/M6_questions.html

would someone be able to write down the rules and what they are used for.
possibly even answer a few q's.

i searched forum for a trig topic and couldnt find a topic dedicated to it, so sorry for reposting again :$

 

[word.]

you press the degrees minutes seconds button
[^o' "] <-- assuming you have a casio calc

remember your trig ratios for q1

tan30 = 120/(x + BC)

tan50 = 120/BC

BC = 120/tan50

1/sqrt(3) = 120tan50/(xtan50 + 120)

xtan50 + 120 = 120*sqrt(3)*tan50

x = (120*sqrt(3)*tan50 - 120)/tan50

so the answer is 107.2^o

 

[sally_33]

Some general tips for trigonometry:



IF THE PROBLEM HAS A RIGHT ANGLE USE THE

SIN= Opp/Hyp

COS = adj/hyp

TAN = opp/adj

or it may even involve pythagoras. just make sure you dont over complicate things - ive spent ages trying to work trig out before only to realise it just needs simple year 8 pythagoras!



For non-right angeled trig problems they will usually give you 3 pieces of information and you will have to find a fourth. So..

If the problem involves two sides and two angles - use sine rule
i.e. a/ sinA = b/sinB = c/sinC

If the problem involves three sides and one angle - use cosine rule. There are two and you'll find them on the formula sheet.