Question

Position vectors m and n have terminal points of (2, ) and (1, y), respectively.

If m · n = 8, then y is _____.
A. 4 1/2
B. 6 1/2
C. 8
D. 12

Answer 1

The answer is C or 8.

Explanation:

Answer 2

This problem involves the dot product.

You must provide all info for position vector m. Your (2,) is inadequate.

Supposing that the terminal point of vector m were (2,3), then

m dot n would equal 8, or 8 = 2*2+3*y. Then 8 = 4 + 3y, and 4 = 3y, and y =3/4.

Please type in the terminal point of vector m and then answer this question following the above example.