G Guest Guest Jul 15, 2006 #1 If im given a value for a double angle, such as Cos 2A = 7/18, how do I find possible values of Sin A and Cos A?
If im given a value for a double angle, such as Cos 2A = 7/18, how do I find possible values of Sin A and Cos A?
M Mrspi Senior Member Joined Dec 17, 2005 Messages 2,116 Jul 15, 2006 #2 Alexyboy said: If im given a value for a double angle, such as Cos 2A = 7/18, how do I find possible values of Sin A and Cos A? Click to expand... cos 2A = 2 cos<sup>2</sup> A - 1 and cos 2A = 1 - 2 sin<sup>2</sup> A Substitute 7/18 for cos 2A, and solve for the possible values of sin A and cos A.
Alexyboy said: If im given a value for a double angle, such as Cos 2A = 7/18, how do I find possible values of Sin A and Cos A? Click to expand... cos 2A = 2 cos<sup>2</sup> A - 1 and cos 2A = 1 - 2 sin<sup>2</sup> A Substitute 7/18 for cos 2A, and solve for the possible values of sin A and cos A.
