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# Core 4 Finding minimum value of trig equation

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1. I know how to get max value but not min value q b i and ii
R = SQUARE ROOT 10
a is 1.25
2. (Original post by koolgurl14)
I know how to get max value but not min value q b i and ii
R = SQUARE ROOT 10
a is 1.25
The minimum value of is , so the minimum value of and this occurs precisely when or some other reasonable value.
3. Easiest way to do this is to say what value of sin(.....) makes sqrt10 sin(.....) as small as possible. Given as you know that sin(...) ranges from -1 to 1, the smallest value occurs when sin(......) is -1, so the minimum value is -sqrt10. As for the second part, you know that sin(x-1.25)=-1, so just solve for x.
4. (Original post by Zacken)
The minimum value of is , so the minimum value of and this occurs precisely when or some other reasonable value.
Hmm what about R>0 or does that not affect the results
its the right answer btw im just asking why we should ignore the R>0
5. (Original post by koolgurl14)
Hmm what about R>0 or does that not affect the results
its the right answer btw im just asking why we should ignore the R>0
What do you mean by ignoring ?

We have an expression . To minimise this, we look at the variable terms and notice that is bounded between -1 (minimum) and 1 (maximum), so to maximise our entire function we pick the minimum sine value and hence say that the minimum of .
6. (Original post by koolgurl14)
Hmm what about R>0 or does that not affect the results
its the right answer btw im just asking why we should ignore the R>0
R>0 only applies to finding the value of R
7. Ahhh I see what you mean its just cause in the question it says the range of R is R>0 so I got confused but I guess its not actual R being less than 0?
8. (Original post by koolgurl14)
Ahhh I see what you mean its just cause in the question it says the range of R is R>0 so I got confused but I guess its not actual R being less than 0?
Ohh, it just means that when you do then you have but since you pick since
9. (Original post by Zacken)
Ohh, it just means that when you do then you have but since you pick since

ohhhhhh that makes a lot of sense thanks alot
10. (Original post by koolgurl14)
ohhhhhh that makes a lot of sense thanks alot
No problem!

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