Calculate, correct to one decimal place, the angle betwee...
Calculate, correct to one decimal place, the angle between 5i + 12j and -2i + 3j.
54.8°
56.3°
66.4°
76.3°
Correct answer is B
a.b=|a||b|cosθ
(5i+12j).(2i+3j)=−10+36=26
26=|5i+12j||−2i+3j|cosθ
|5i+12j|=√52+122=√25+144=13
|2i+3j|=√22+32=√4+9=√13
26=13(√13)cosθ
cosθ=2613√13=0.5547
\theta = 56.3°