The angle between two vectors is:
CosФ = u - v / Magnitude(u) x magnitude(v)
Magnitude of u = SQRT(7^2 + -2^2) = SQRT(49 +4) = SQRT(53)
Magnitude of v = SQRT(-1^2 +2^2) = SQRT(1 +4) = SQRT(5)
u x v = (7 x -1) + (-2 x 2) = -7 + -4 = -11
cosФ = -11 / sqrt(53) x sqrt(5)
cosФ = -11sqrt265) / 265
Ф =cos^-1(-11sqrt265) / 265)
Ф=132.51 degrees.
X>Y
X=7Y
3X=7+4Y
X=?
Y=?
----------------------------
3*7=7+4Y
21Y=7+4Y
21Y-4Y=7
17Y=7
Y=7/17
----------------------
X=7*7/17
X=49/17
Answer: the answer is 2 teaspoons of vanilla extract.
hope this helped
