c3 maximum/minimum value using Rsin(x+..)

How do i do these 2marker questions? I always get confused!
If it is a minimum, to find the smallest value of x, do I equate the trig part to -1, and if max 1?

Reply 1

AnonyMatt

-1 <= sin(x+a) <= 1

-R <= Rsin(x+a) <=R

Reply 2

blazing999

more easily...

Sketch the graph of either cos or sin
stretch the max or min by the 'R' term

so 5cos(x-a) will have a max when cos was zero. this value now becomes 5 and has a minimum of -1 at 180 and this will now be -5

You may have to shift the wave depending on the a value but the max will still be 5 and min -5 on this example

Reply 3

Doc(1/cosC)

the R value is always the maximum or minimum, and then pheta (that fish sign in the bracket) is always the value that gives this maximum or minimum value... simples?!

Reply 4

blazing999

Doc(1/cosC)

the R value is always the maximum or minimum, and then pheta (that fish sign in the bracket) is always the value that gives this maximum or minimum value... simples?!

This has already been stated if you bothered to follow the posts before...

'theta' BTW

Reply 5

Doc(1/cosC)

blazing999

This has already been stated if you bothered to follow the posts before...

'theta' BTW

OMG not everyone has the time to read the whole spread!?!, and exams have finished so i dont see why i should be reading information anywayz and correcting my volcabulary ?!!