Solving Trig Equations Exact Values C A S T 0 o 180 o 270 o 90 o 180 o - x o 180 o + x o x o 360 o + x o CAST diagram undefined 0 1 0 1 3 1 2 2 3 1 1 1 2 2 3 1 3 2 2 1 0 o o o o o sin cos tan 0 30 45 60 90 ALWAYS work with 1 st Quad then translate olve: tanx o + 1 = 0 tanx o = -1 x o = tan -1 (1) x o = 45 o Solution : x o = 180 o - 45 o = 135 o x o = 360 o - 45 o = 315 o Exampl e 1 -1 0 90 o 180 o 270 o 360 o 45 o θ Find x coordinates for A and B A B 0.4 sinx o = 0.4 x o = sin -1 (0.4) x o = 23.6 o x o =180 o - 23.6 o = 156.4 o C A S T 0 o 180 o 270 o 90 o C A S T 0 o 180 o 270 o 90 o