maths Question (20)

ci) The equation can be expressed as
cosx+2=x/30
By the simultaneous equation
y=cosx+2 and
y=x/30

..........

cii) The equation can be expressed as
cosx+2=2+x/20
By the simultaneous equation
y=cosx+2 and
y=2+x/20

..........

其實，這一題是要用函數的圖像來解決的。
只要閣下會畫cosine curve(以符合b部要求)以及所需的直線就行了。

(c)(i)
you have the graph of y=cos x+2
Now consider a straight line y=x/30
Then the intersection point of the curve and straight line is
x/30=cos x + 2 or cos x - x/30 = -2
So you only need to draw a straight line y=x/30 and locate the intersection point
(ii)
Now consider a straight line y=x/20 + 2
Then the intersection point of the curve and straight line is
x/20 + 2 = cos x + 2 or cos x - x/20 = 0
So you only need to draw a straight line y=x/20 + 2 and locate the intersection point