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Trig Function

the function g(x) is c+d sinx the range of g is given by -4<g(x)<10
find values of constant c and d.i know max value of sinx graph is 1 and min is -1 so if i substitute in for x i get the answer but just wanted to know isn't the max and min 1 and -1 only when no change is made to sinx graph because here the graph has been transformed right, so max and min are no more at 1 and -1. can someone clear this out for me.
Original post by papie
the function g(x) is c+d sinx the range of g is given by -4<g(x)<10
find values of constant c and d.i know max value of sinx graph is 1 and min is -1 so if i substitute in for x i get the answer but just wanted to know isn't the max and min 1 and -1 only when no change is made to sinx graph because here the graph has been transformed right, so max and min are no more at 1 and -1. can someone clear this out for me.


You are right, max and min of +1 and -1 occur when you are only dealing with sinx\sin x on its own.

But it's not difficult to obtain max and min for the transformed graph;

1sinx1-1 \leq \sin x \leq 1

Multiply through by dd;

ddsinxd-d \leq d \sin x \leq d

Add cc to everything;

cdc+dsinxc+dc-d \leq c+d\sin x \leq c+d


So the min and max values are precisely just cdc-d and c+dc+d repsectively.
(edited 4 years ago)
Reply 2
Original post by RDKGames
You are right, max and min of +1 and -1 occur when you are only dealing with sinx\sin x on its own.

But it's not difficult to obtain max and min for the transformed graph;

1sinx1-1 \leq \sin x \leq 1

Multiply through by dd;

ddsinxd-d \leq d \sin x \leq d

Add cc to everything;

cdc+dsinxc+dc-d \leq c+d\sin x \leq c+d


So the min and max values are precisely just cdc-d and c+dc+d repsectively.

thanks :biggrin:

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