Question: A student is given that point P(a, b) lies on the terminal ray of angle Theta, which is between StartFraction 3 pi Over 2 EndFraction
A student is given that point P(a, b) lies on the terminal ray of angle Theta, which is between StartFraction 3 pi Over 2 EndFraction radians and 2Pi radians. The student uses the steps below to find cos Theta. Step 1 Find the quadrant in which P(a, b) lies: P(a, b) is in Quadrant IV. Step 2 Use the point and the Pythagorean theorem to determine the value of r: r = plus-or-minus StartRoot (a squared) + (b squared) EndRoot, but since r must be positive, r = StartRoot a squared + b squared EndRoot. Step 3 Determine cos Theta. cosine theta = StartFraction negative a Over StartRoot a squared + b squared EndRoot EndFraction = Negative StartFraction a StartRoot a squared + b squared EndRoot Over a squared + b squared EndRoot EndFraction, where a and b are positive. Which of the following explains whether the student is correct? The student made an error in step 3 because a is positive in Quadrant IV; therefore, cosine theta = StartFraction a Over StartRoot a squared + b squared EndRoot EndFraction = StartFraction a StartRoot a squared + b squared EndRoot Over a squared + b squared EndFraction. The student made an error in step 3 because cosine theta = StartFraction negative b Over StartRoot a squared + b squared EndRoot EndFraction = Negative StartFraction b StartRoot a squared + b squared EndRoot Over a squared + b squared EndFraction. The student made an error in step 2 because r is negative in Quadrant IV; therefore, r = Negative StartRoot a squared + b squared EndRoot. The st
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