- #1
Aaron H.
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Homework Statement
Given the magnitudes of vectors u and v and the angle θ between them, find sum of u + v. Give the magnitude to the nearest tenth when necessary and give the direction by specifying the angle that the resultant makes with u to the nearest degree.
Homework Equations
|u| = 15, |v| = 15, θ = 116°
The Attempt at a Solution
Knowing only the answer (15.9, 58°) and some trig ideas:
I draw an angle of 116 degrees in the starting point of the trig plane. I drop a line from the angle end side, forming a triangle with a 64 degree angle in quadrant II. The other angles of the triangle are both 58 degrees (116 deg / 2). Both opposite (U) and adjacent (V) sides are 15.
SAS - law of cosines
c^2 = (15)^2 + (15)^2 - 2 (15)(15) cos (64 deg)
c = 15.9
angle = 58 deg
(15.9, 58 deg)
What is the correct method?