Use the definition of scalar product, a overscript right-arrow endscripts times b overscript right-arrow endscripts = ab cos θ, and the fact that a overscript right-arrow endscripts times b overscript right-arrow endscripts = axbx + ayby + azbz to calculate the angle between the two vectors given by a overscript right-arrow endscripts equals 3.0 i overscript ̂ endscripts plus 3.0 j overscript ̂ endscripts plus 3.0 k overscript ̂ endscripts and b overscript right-arrow endscripts equals 5.0 i overscript ̂ endscripts plus 7.0 j overscript ̂ endscripts plus 6.0 k overscript ̂ endscripts.