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| Question 1174405:  1.Given: cos theta = 5/13, theta is in quadrand I. Find:tan  theta.
 2.Given:sin theta=1/3,theta is in quadrand II. Find:cos theta.
 3.Given:tan theta =2/3 theta is in quadrand IV. Find:sin theta.
 4.Given:sec theta=9/8,theta is in quadrand III . Find:csc theta.
 5.Given:csc theta= 2, sec theta < 0. Find tan theta.
 6:Given:cot theta= 8/15, sin theta < 0.find cos theta.
 Answer by Theo(13342)
      (Show Source): 
You can put this solution on YOUR website! 1.Given: cos theta = 5/13, theta is in quadrant I. Find:tan theta. 
 arccos(5/13) = 67.38013505 degrees.
 that's in quadrant 1.
 equivalent angle in quadrant 1 is the same.
 tan(67.38013505) = 2.4
 
 2.Given:sin theta=1/3,theta is in quadrant II. Find:cos theta.
 
 arcsin(1/3) = = 19.47122063 degrees.
 that's in quadrant 1.
 equivalent angle in quadrant 2 is 180 minus that = 160.5287794.
 cos(that) = -.9428090416.
 cosine function is negative in quadrant 2.
 
 3.Given:tan theta = 2/3 theta is in quadrant IV. Find:sin theta.
 
 arctan(2/3) = 33.69006753 degrees.
 that's in quadrant 1.
 equivalent angle in quadrant 4 is 360 minus that = 326.3099325.
 sin(that) = -.5547001962.
 sine function is negative in quadrant 4.
 
 4.Given:sec theta=9/8,theta is in quadrant III . Find:csc theta.
 
 sec(theta) = 1/cos(theta), therefore:
 since secant = 1/cosine, then:
 1/cos(theta) = 9/8.
 solve for cos(theta) to get cos(theta) = 1/(9/8) = 8/9.
 arccos(8/9) = 27.26604445 degrees.
 that's in quadrant 1.
 equivalent angle in quadrant 3 is 180 plus that = 207.2660445
 csc(that) = 1/sin(that) = -2.182820625.
 cosecant is negative in third quarter because cosecant = 1/sine and sine is negative in quadrant 3.
 
 
 5.Given:csc theta= 2, sec theta < 0. Find tan theta.
 
 csc(theta) = 1/sin(theta).
 solve for sin(theta) to get sin(theta) = 1/2.
 arcsin(1/2) = 30 degrees.
 that's in quadrant 1.
 sec(theta) is smaller than 0.
 sec(theta) is equal to 1/cos(theta) and is negative in quadrants 2 and 3.
 the equivalent angle in quadrant 2 is 180 - 30 = 150 degrees.
 tan(150) = -.5773502692.
 tangent function is negative in quadrant 2.
 the equivalent angle in quadrant 3 is 180 + 30 = 210 degrees.
 tan(210) = .5773502692.
 the tangent function is positive in quadrant 3.
 this is because sine is negative and cosine is negative in quadrant 3 and tangent = sin/cos = negative/negative = positive in quadrant 3.
 it's the same value as in quadrant 2 only it's negative in quadrant 2 and positive in quadrant 3.
 
 6:Given:cot theta= 8/15, sin theta < 0.find cos theta.
 
 cot(theta) = 1/tan(theta) = 8/15
 solve for tan(theta) to get tan(theta) = 15/8.
 arctan(15/8) = 61.92751306 degrees.
 that's in quadrant 1.
 sin(theta) is negative in quadrant 3 and 4.
 equivalent angle in quadrant 3 is 180 plus that = 241.9275131 degrees.
 cos(that) = -.4705882353.
 cosine is negative in quadrant 3.
 equivalent angle in quadrant 4 is 360 minus that = 298.0724869 degrees.
 cos(that) = .4705882353.
 cosine is positive in quadrant 4.
 
 if you are confused or have any questions about any of this, let me know and i'll explain as best i can.
 
 theo
 
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