 In this video, we provide the solution to question number six for practice exam number three for math 1060 We're given a vector whose magnitude is equal to 10 and whose erection is theta We're not given the angle theta directly, but we do know that it's in the first quadrant and the sign ratio is three-fifths We then want to compute the horizontal component of v now the vertical component v y this equals the magnitude 10 Times sine of theta so if they had one of the vertical component that'd be a lot easier The horizontal component is going to be vx which is 10 times the cosine of theta the magnitude times cosine of the direction For which we have to compute cosine real quick You don't have a calculator, but we can do this easy enough, right? If this is angle theta sine is opposite over hypotenuse by the Pythagorean relationship the other side the adjacent side should be 4 therefore cosine is Going to equal four fifths five goes into ten two times you get two times four Which is equal to eight and so we see the correct answer is choice B