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secondary 3 | A Maths
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please help with this question, thank you!
Date Posted: 4 years ago
Views: 306
cos(x+30°)
= cosxcos30° - sinxsin30°
= √3/2cosx - 0.5sinx
so
3cos(x+30°) = 4sinx
3√3/2cosx - 3/2sinx = 4sinx
3√3/2cosx = 4sinx + 3/2sinx
3√3/2cosx = 11/2sinx
3√3cosx = 11sinx
11sinx - 3√3cosx = 0
cosx(11tanx - 3√3) = 0
cosx = 0 or tanx = 3√3/11
x = 90°, 270° ; or x = 25.3°, 205.3°
...
= cosxcos30° - sinxsin30°
= √3/2cosx - 0.5sinx
so
3cos(x+30°) = 4sinx
3√3/2cosx - 3/2sinx = 4sinx
3√3/2cosx = 4sinx + 3/2sinx
3√3/2cosx = 11/2sinx
3√3cosx = 11sinx
11sinx - 3√3cosx = 0
cosx(11tanx - 3√3) = 0
cosx = 0 or tanx = 3√3/11
x = 90°, 270° ; or x = 25.3°, 205.3°
...
thank you so much!
x=90 and x=270 isn't correct
Will write my version by posting of my scanned answers.
See 1 Answer
done
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Here
Date Posted:
4 years ago
thank you so much!
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