q^2 - r^2 - p^2 = -2rp cos Q
( q^2 - r^2 - p^2 over -2rp ) = cos Q
Q= cos -1 ( q^2 - r^2 - p^2 over -2rp )
Q=cos -1 ( (12.4)^2 - (6.3)^2 - (7.3)^2 over -2(6.3)(7.3) )
Q= 101 degrees
I'm not getting anything close to 101. Can soembody maybe tell me what to punch in because maybe i'm putting it in wrong.
更新1:
sorry. Q= 131 not 101.