The line segment with endpoints (−20, 21) and (0, 0) is graphed on the standard coordinate plane and makes an angle, Θ, with respect to the x axis. What is cos Θ? A) − 20 29 B) − 29 20 C) − 20 21 D) 21 29
see the attached figure to better understand the problem Let A (−20, 21) B (0, 0)
step 1 find the distance AB d=√[(y2-y1)²+(x2-x1)²]------> d=√[(0-21)²+(0+20)²] d=√841------> d=29 units
step 2 find cos ∅
cos ∅=adjacent side angle ∅ /hypotenuse adjacent side angle ∅=20 units hypotenuse=distance AB=29 units so cos ∅=-20/29-----> is negative because ∅ belong to the II quadrant
