A student is given that point P(a, b) lies on the terminal ray of angle , which is between radians and 2 radians. The student us
es the steps below to find cos . 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: , but since r must be positive, . Step 3 Determine cos . , 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, . The student made an error in step 3 because . The student made an error in step 2 because r is negative in Quadrant IV; therefore, . The student made an error in step 2 because using the Pythagorean theorem gives .
