Homework Help Forum: trig

Posted by kt on Monday, October 12, 2009 at 7:40pm.

Point P is located at the intersection of a circle with a radius of r and the terminal side of an angle q. Find the coordinates of p to the nearest hundreth. q = -60° , r = 7

• trig - Reiny, Monday, October 12, 2009 at 8:09pm

  Assuming you are using angle rotation convention, that would put point P into the 4th quadrant. After drawing the triangle with hypotenuse of 7 and angle of 60º, we can see that sin -60 = y/7 ----> y = 7(sin -60º) = -6.06 cos -60º = x/7 = 7cos -60º = 3.5 so P is (3.5,-6.06) or we could have used the ratios of sides of the 30-60-90 triangle which are 1:√3:2 then x:y:7 = 1:√3:2 x/1 = 7/2 ---> x = 3.5 y/√3 = 7/2 ---> y = 7√3/2 = 6.06 Realizing where P is located, P is (3.5,-6.06)

  
  

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