2016年6月9日 · How do you use the ordered pairs on a unit circle to evaluate a trigonometric function of any angle

2018年7月3日 · How do you evaluate #cos ((4pi)/3)#? Trigonometry Right Triangles Trigonometric Functions of Any Angle. 1 ...

2018年3月7日 · #cos(pi/4)=sqrt(2)/2#, refer to the explanation below for how to find the exact value without a calculator. Explanation: It is possible to find the exact value of #cos(pi/4)# by constructing a right triangle with one angle set to #pi/4# radians.

2018年4月13日 · sqrt2/2 As you can see in the table above, cos45^@ or cospi/4 radians is the same thing as sqrt2/2 An alternative way is looking at the unit circle: We know that the cosine of an angle is the x-value of a coordinate. At pi/4, we can see that the x-value is sqrt2/2. Therefore, cos(pi/4) = sqrt2/2 Hope this helps!

2016年5月2日 · Why is cos(4pi/3) = - cos(pi/3)? Trigonometry Right Triangles Relating Trigonometric Functions. 1 Answer

2016年7月3日 · -1/2 Use the trig identity: cos 2a = 2cos^2 a - 1 cos ((4pi)/3) = 2cos^2 ((2pi)/3) - 1 Trig table gives: cos ((2pi)/3) = -1/2.

2016年8月15日 · Trig table of special arcs, and unit circle --> #cos ((-4pi)/3) = cos ((4pi)/3) = cos (pi/3 + pi) = - cos (pi/3) = -1/2#

2015年7月5日 · An angle of (4pi)/3 is in Quadrant 3 with a reference angle of pi/3 sin((4pi)/3) = -sqrt(3)/2 cos((4pi)/3) = -1/2 tan((4pi)/3) = sqrt(3) See diagram below: Note that pi/3 is one of the standard trigonometric angles.

2016年10月3日 · #cos(pi/7)cos((4pi)/7) cos((5pi)/7)# #=4/(8sin(pi/7))xx(2sin(pi/7)cos(pi/7))cos((4pi)/7)cos(pi-(2pi)/7)# #=-2/(8sin(pi/7))xx(2sin((2pi)/7)cos((2pi)/7))cos((4pi)/7)#

2017年2月17日 · Use trig table of special arcs and unit circle. On the unit circle, #sin ((4pi)/3) = - sin (pi/3) = - sqrt3/2# #cos ((4pi)/3) = - cos (pi/3) = - 1/2#