Date: 6/22/96 at 9:54:16 From: Igor Srdanovic Subject: Trig. Equation Hi! I have a math problem. It's an equation. Hope you can solve it. (cos(x))^2+(sin(x))^2=(15*(cos(x))^2)/18)-(1/2) x=?
Date: 6/22/96 at 11:8:49 From: Doctor Anthony Subject: Re: Trig. Equation As you have written the equation, the left hand side will equal 1. The equation then can be written: (15/18)cos^2(x) - 1/2 = 1 (5/6)cos^2(x) = 3/2 cos^2(x) = 18/10 cos^2(x) = 1.8 cos(x) = sqrt(1.8) = 1.34164 There can be no real solution to this equation since -1 < or = cos(x) < or = 1 for real x. I have some doubts about the equation you have written down, particularly as the left hand side immediately simplifies to 1. Perhaps you can check it and post a correction if necessary. -Doctor Anthony, The Math Forum Check out our web site! http://mathforum.org/dr.math/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994-2015 The Math Forum