4. the point ps0.5, 0d lies on the curve y − cos ? x. (a) if q is the point sx, cos ? xd, use your calculator to ind the slope of the secant line pq (correct to six decimal places) for the following values of x: (i) 0 (ii) 0.4 (iii) 0.49 (iv) 0.499 (v) 1 (vi) 0.6 (vii) 0.51 (viii) 0.501 (b) using the results of part (a), guess the value of the slope of the tangent line to the curve at ps0.5, 0d. (c) using the slope from part (b), ind an equation of the tangent line to the curve at ps0.5, 0d. (d) sketch the curve, two of the secant lines, and the tangent line.