Use substitution to determine whether the given X-value is a solution of the equation.
cos 2x/3 = -1/2, x = Pi
2007-11-30 18:07:55 · 2 answers · asked by ambriz_jesus9 1 in Science & Mathematics ➔ Mathematics
Test the value of x = π :-
cos (2π / 3) = - 1 / 2
Thus x = π IS a solution.
2007-11-30 21:51:06 · answer #1 · answered by Como 7 · 3⤊ 1⤋
-plug pi in for x: cos 2(pi)/3 = -1/2
-now refer back to the unit circle *here's a link*
http://www.hsu.edu/uploadedImages/Faculty/lloydm/classes/pt/UnitCircle.GIF
-find the radian 2pi/3 (120 degrees) and look at the cosine value/ x-value
- the cosine of 2pi/3 is -1/2 so the answer is a solution
*this may sound completely INSANE but it really helps to memorize the unit circle-like the entire thing. it saves you so much work and time and comes in handy when you have to find complementary/ suplementary angles and when calculation secants, cosecants, tangents, and cotangents.
2007-11-30 18:20:25 · answer #2 · answered by bunnie <3 5 · 1⤊ 1⤋