Question

express sin 205degrees in terms of the sine of a positive acute angle. Do not evaluate.

Answer 1

an airplane propeler blade is 2.80ft, and rotates @ 2200 r/min. What is the linear velocity of a point on the tip of the blade?

Answer 2

have you learned about special trig rules with trig functions?

Answer 3

please explain?????????????????????????

Answer 4

would i have learned about this in geomiyt/?

Answer 5

ok I'm sure now, for sin(205) to have it be an acute angle it has to be less than 90, and sin(25) works and is positive

Answer 6

Then your propeller one is difficult to explain, I found the same problem that is explained here on page 16 http://www.nunamaker.com/mathlady/Math%20181%20Chapter%2010%20Trig%20Functions%20Term%200306.pdf

Answer 7

Let me explain this and please tell me if I got it or not?

Answer 8

sin is positive in qued 1 or 2, so u subtract from 205 untill u get to 180? hence the 25.

Answer 9

um well not quite. So first info is given that the angle needs to be acute. And an acute angle must be less than 90 degrees, and this is taught in geometry. So by that definition, you know you are looking for an angle in the first quadrant. Second, it tells you need sin that is equivalent to sin(205) so hopefully with this picture it will help

Answer 10

so by using those rules 1. acute is less than 90 degrees 2. sin must be positive 3. the angle you are looking for has paired angle. you find the angle by 205-180 because you are looking for an angle that is exactly half around the unit circle which is 360 degrees

Answer 11

so the acute angles of A & B have the same degree measurement?

Answer 12

yup, only difference is one is negative and the other positive. if you have a calculator you can show yourself they are the same too. sin(205)=sin(25)

Answer 13

cool learning is fun! when i put sin(25) in my calculator i get 0.422.

Answer 14

haha sure is, and ye, the point of me telling you to try your calculator was to see that the decimal answer you get for sin(205) is the same as sin(25) just one is + and the other -

Answer 15

so sin (205) should be -0.422