Question

What is the angle between a=7i+3j and b=4i-j​

Answer 1

`a\cdot b=(7)(4)+(3)(-1)=25\\\\|a|=\sqrt{7^(2)+3^(2)}=√(58)\\\\|b|=\sqrt{4^(2)+(-1)^(2)}=√(17)\\\\\cos \theta=(25)/(√(58)√(17))\\\\\theta=\cos^(-1) \left((25)/(√(58)√(17)) \right) \approx 37.235^(\circ)`