Sinusoidal Functions (I for this)

[mathuravasant]

Sinusoidal Functions... Can someone help me with this.
Describe the transformations that are applied to y= -4cos[2(x-30°)] +5 (State any shifts, stretches, compressions, or reflections).

 

[skeeter]

parent function is $y = \cos{x}$

$y = A\cos[B(x - C)] + D$

$|A|$ = amplitude

$B = \dfrac{2\pi}{T}$ , where $T$ is the period

$C$ = horizontal shift

$D$ = vertical shift

 

[mathuravasant]

Thanksss but I am garbage at math :/

 

[skeeter]

Thanksss but I am garbage at math :/

Maybe you should get some extra instruction ...

 

[mathuravasant]

Thanks

 

[mathuravasant]

Hey, How do you do this question:

Find the first two positive x-intercepts for y= -2cos(3(x-25°)) +1

 

[skeeter]

x-intercepts $\implies y = 0 \implies \cos[3(x-25^\circ)] = \dfrac{1}{2}$

from the unit circle, and the fact that cosine is an even function, note that $\cos(60^\circ) = \cos(-60^\circ) = \dfrac{1}{2}$

$3(x-25^\circ) = -60^\circ$

$3(x-25^\circ) = 60^\circ$

 

[mathuravasant]

thanks what do you do for this question:

A sinusoidal function has an amplitude of 3, period of 180 degree, and a minimum at (45 degree, -2). Write the equation for the transformed cosine function.

 

[skeeter]

sketch a graph and write an equation ...

 

[topsquark]

thanks what do you do for this question:

A sinusoidal function has an amplitude of 3, period of 180 degree, and a minimum at (45 degree, -2). Write the equation for the transformed cosine function.

Perhaps you should start showing us what you know and can do. If you can't do the problem at least tell us what you are looking for. For example, for this last one, even if you don't know how to get it started at least tell us what the definition of period and amplitude are. We need to know why you are having so much trouble and giving you answers is apparently not helping.

-Dan