T(t)=20+5cos(pi/12(t-3)) where T is the temperature . When was temp below 17.5C
When graphing time is on the x axis and temp on y?

Question

T(t)=20+5cos(pi/12(t-3)) where T is the temperature  .  When was temp below 17.5C
When graphing time is on the x axis and temp on y?

perl · Answer

you can graph T(t)=20+5cos(pi/12(t-3)) and T = 17.5 and see where they intersect

anonymous · Answer

this is a weird question or I am missing something but temp at noon is 23.5 and by calculations it say min will occur at 15 and max at 3 bizarre, shouldn't it be the other way around?

perl · Answer

yes that is odd

perl · Answer

wait, is T temperature since noon?

anonymous · Answer

i have checked and checked

perl · Answer

t= 0 corresponds to noon temperature

perl · Answer

can you also post the directions to the last question , that would help

anonymous · Answer

ahhhhhhh yes, thank you, thought I was going nutty, should read the question properly LOL

perl · Answer

yes that makes sense, min occurs at t = 15 hours after noon, and max occurs t = 3 hours after noon

perl · Answer

now for the question above

perl · Answer

can i send you a link

perl · Answer

https://www.desmos.com/screenshot/lusqpaxs9t

anonymous · Answer

so it is best if I draw a line through at 17.5?

anonymous · Answer

That would be excellent or can I just do it on desmos?

perl · Answer

yes

anonymous · Answer

cool :)

perl · Answer

you have to zoom out though https://www.desmos.com/calculator/o3gakiua8i

perl · Answer

scroll down to zoom out

anonymous · Answer

$$f(x)=2-\sqrt{x/2+3}$$
How do I work out the range of this function?

perl · Answer

the range of y= sqrt(x)  is [0,oo)
the range of y = -sqrt(x) is (-oo,0] 
then add to two that

(-oo, 2]

perl · Answer

alternatively you can graph the function into desmos

anonymous · Answer

thanks again :)

anonymous · Answer

Are you still there?