# Math Help - Revision for Standard Grades and need Help

1. ## Revision for Standard Grades and need Help

I am revising with past papers for the 2009 Standard Grade Credit Maths. Would appreciate some help with the following past paper example.

Solve algebraically the equation

5 cos xo + 4=0, 0 ≤ x ≤ 360

If anyone knows where I would be able to obtain Standard Grade Credit past paper exemplar answers (that show working not just the end result) would much appreciate if you could let me know

I have only got around 2 months left to exam time and need all the help I can get

Thanks in anticipation

2. Originally Posted by drew1000
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Solve algebraically (are you sure?) the equation

5 cos xo + 4=0, 0 ≤ x ≤ 360

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According to the wording of your question the argument of the cos-function is in degrees.

$5\cos(x)+4=0~\implies~\cos(x)=-\dfrac45~\implies~x\approx 143.13^\circ\vee x\approx360^\circ-143.13^\circ\approx 216.87^\circ$

3. Originally Posted by drew1000
If anyone knows where I would be able to obtain Standard Grade Credit past paper exemplar answers (that show working not just the end result) would much appreciate if you could let me know
Goto Maths -> Standard Grade -> Exam Solutions at the following: