Posted by Trig on Tuesday, November 3, 2009 at 8:27pm.
225º is in the fourth quadrant, 45º below the first quadrant, so its x value is indeed positive.
Check how angles are measured.
I think i was in radians my bad
um how come tan of 300 is negative root three
tangent in unit circle is y/x I am getting .5/(root three/2)
which is not root three
Forget about my previous post.
Obviously 225º is in the third quadrant, 45º below the second quadrant like you said.
So of course cos 225 is negative.
tan 300º
= -tan 60º by the CAST rule
= -√3/1 from the ratios of the 30-60-90 triangle
= -√3
why wouldn't you use the 30 degree angle?
I did 360 -90 to get 270 degrees and then did 300 - 270 to get 30 degrees and used that angle why would I use the 60 degree angle instead of the thirty
Always ask yourself,
"How far away from the x-axis am I "?
to get the reference angle.
e.g. sin 160
160º is 20º away from the x-axis and according to the CAST rule in quadrant II the sine is positive, so
sin 160º
= sin 20º
e.g. tan 310º
310º is 50º from the x-axis and according to the CAST rule, in quadrant IV the tangent is negative, so
tan 310
= -tan 50
check my examples with your calculator
Related Questions
trig - How do I get exact measures? cosine 270 degrees sin 90 degrees tan 360 ...
trig identities - cos94 degrees cos18 degrees+ sin94 degrees sin18 degrees. ...
Spherical Trigonometery - I am trying to apply the formula cos c = cos a x cos b...
trignometry - use degree measure for your answers. use a calculator and round ...
Trig - I'm confused on how to determine what the end result angles are for a...
Coterminal Angles - I need help with this.. it's for my midterm review. My ...
trig - Find the reference angle for each given angle: a) 325 degrees b) 14pi/3 c...
trig - Determine if the value of each trig function is positive, negative, zero...
trig - give exact value of cos 75 degrees. give exact value sin 15 degrees. give...
trig help - I need help finding sinA if cosA=(-3/5) and A is greater than 90 ...
For Further Reading
