The Student Room Group
irish_4_life
So how do you solve (for between 0 and 360)

sin(theta + 40) = 0.7

I'm majorly struggling with this chapter :s-smilie: I don't have a clue what to do!

Thanks all x


theta + 40 = arcsin(0.7)

Remember that you've got to find theta in the range 0 to 360 so you have to be careful which solutions you include.
Reply 2
irish_4_life
So how do you solve (for between 0 and 360)

sin(theta + 40) = 0.7

I'm majorly struggling with this chapter :s-smilie: I don't have a clue what to do!

Thanks all x


Let θ+40=ϕ \theta + 40 = \phi

find all the values for phi and then take away 40 from each. Simple!
Reply 3
Do you not do sin^-1 0.7 thing on the calculator which leaves you with (x + 40) then subtract your answer by 40 to get x. Once you have x find the other values by sketching the graph of sin.
I think :biggrin:
sin(θ+40) = 0.7
so
(θ+40) = 44.4 and also 180-44.4

θ+40 = 44.4 , 135.6

θ = 4.4 , 95.6
at18
Do you not do sin^-1 0.7 thing on the calculator which leaves you with (x + 40) then subtract your answer by 40 to get x. Once you have x find the other values by sketching the graph of sin.
I think :biggrin:


Personally i prefer to do it without a graph, i hate sketching :p: i just use CAST system :smile:

Personal preference really.
Long Haired Teen
sin(θ+40) = 0.7
so
(θ+40) = 44.4 and also 180-44.4

θ+40 = 44.4 , 135.6

θ = 84.4 , 175.6


These two lines do not follow on.
Reply 7
Long Haired Teen
Personally i prefer to do it without a graph, i hate sketching :p: i just use CAST system :smile:

Personal preference really.

I would probably prefer that too :smile: ... if I knew what the CAST system was lol :rolleyes:
Clarity Incognito
These two lines do not follow on.


Very well spotted :colondollar: Thanks, this is what i get for trying to multitask
Reply 9
at18
I would probably prefer that too :smile: ... if I knew what the CAST system was lol :rolleyes:


In the quadrant marked A All trig ratios are positive
In the quadrant marked S  the sine ratio is positiive, cos @ tan are negative

etc

Reply 10
Thanks guys, i was looking for something far more difficult!

And yes CAST is a god send, i love it :smile:
Reply 11
steve2005
In the quadrant marked A All trig ratios are positive
In the quadrant marked S  the sine ratio is positiive, cos @ tan are negative

etc


Oh yeah no worries I have seen that before :p:
I think we called it something else, CAST sounds better though!
I thought it was like a computer thing lol :rolleyes: