Trigonometry help!

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A

aclockworkorange

Dovii
MFK Member
Jun 24, 2010
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Rose City
Looking for a little MFK math help...

694f46e8.jpg

Can't use a calculator.

-Is A cos(theta)= -sqrt(11)/4?
I used cos(theta)=sqrt(1-sin(theta)^2)

-B is just a 90 degree negative rotation? But how do I calculate cos? Would it be the same but positive since it's in quadrant I?

-C is just a full rotation so sin would be the same?

-D, E, F are easy once I find sin and cos...

Thanks!


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Hi. this is simple:

A cos(theta)= -sqrt(11)/4 is correct
cos(theta)-pi/2 is the same but positive since all values of trigonometric functions are positive in Q1. only sin is positive in 2.
sin(theta+2pi) is not the same, its sqrt5/4+2pi add the constant k for each subsequent rotation. I don't know how far you need to simplify. I only need to stay exact or three sig figs.
and like you said D is sin/cos
E is the inverse of sin(theta)
F is the inverse of cos(theta)
 
Isnt it sad, I am in Calc. II and i dont remember this trig stuff. I would say set up a Right triangle and use "SOH CAH TOA" and use pythagorean theorem to get your cos value. The Sin inver would give you reference angle in the first quadrant but idk how you would go about finding that without a calc. I never liked trig but I get to relive it every tuesday and thursday :irked:. I feel your pain
 
Theseabean said:
Hi. this is simple:

A cos(theta)= -sqrt(11)/4 is correct
cos(theta)-pi/2 is the same but positive since all values of trigonometric functions are positive in Q1. only sin is positive in 2.
sin(theta+2pi) is not the same, its sqrt5/4+2pi add the constant k for each subsequent rotation. I don't know how far you need to simplify. I only need to stay exact or three sig figs.
and like you said D is sin/cos
E is the inverse of sin(theta)
F is the inverse of cos(theta)
Click to expand...



Thank you for the math lesson Theseabean :footinmou. My professor would be disappointed lol
 
Theseabean said:
Hi. this is simple:

A cos(theta)= -sqrt(11)/4 is correct
cos(theta)-pi/2 is the same but positive since all values of trigonometric functions are positive in Q1. only sin is positive in 2.
sin(theta+2pi) is not the same, its sqrt5/4+2pi add the constant k for each subsequent rotation. I don't know how far you need to simplify. I only need to stay exact or three sig figs.
and like you said D is sin/cos
E is the inverse of sin(theta)
F is the inverse of cos(theta)
Click to expand...

Can you explain C more? Still not getting it. :( Thanks for the answers.


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