# trig help

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#1
Hi, on this paper I am a bit confused on how to do 10b and c. I did 10b but only got 2 out of the 4 solutions using the cos graph, why are there two more solutions. and for 10c, how do you do this. also for question 6 how do you do this also? thanks https://crashmaths.com/wp-content/up...RONZE-P1-A.pdf
0
1 year ago
#2
Can you show your working do far?
When the equation is
cos(x)=0.3
say, where x is 0 to 2,pi, you would get two solutions. When it's
cos(2x)
you'd get four solutions in the range X goes from 0 to 2pi. It's a bit like squaring cos(x), you get more solutions.

To find min or max values, simply take the values that min or max cos().

See how you get on and if ok, I'll comment on 6.

(Original post by Bertybassett)
Hi, on this paper I am a bit confused on how to do 10b and c. I did 10b but only got 2 out of the 4 solutions using the cos graph, why are there two more solutions. and for 10c, how do you do this. also for question 6 how do you do this also? thanks https://crashmaths.com/wp-content/uplowads/2018/09/A2-M-BRONZE-P1-A.pdf
Last edited by mqb2766; 1 year ago
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#3
thanks for the reply. ah yes I see where I went wrong now. how do you do 6?
(Original post by mqb2766)
Can you show your working do far?
When the equation is
cos(x)=0.3
say, where x is 0 to 2,pi, you would get two solutions. When it's
cos(2x)
you'd get four solutions in the range X goes from 0 to 2pi. It's a bit like squaring cos(x), you get more solutions.

To find min or max values, simply take the values that min or max cos().

See how you get on and if ok, I'll comment on 6.

(Original post by Bertybassett)
0
1 year ago
#4
Have you managed to equate the 4 semicircles to the shaded area? Just involves circle areas and an isosceles triangle? If you're stuck, post your working.
(Original post by Bertybassett)
thanks for the reply. ah yes I see where I went wrong now. how do you do 6?
0
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