The range of function y = 2cosx square + 5sinx-4,

The range of function y = 2cosx square + 5sinx-4,

Y = 2cos & # 178; X + 5sinx-4 = 2 (1-sin & # 178; x) + 5sinx-4 = - 2Sin & # 178; X + 5sinx-2 = - 2 (Sin & # 178; X - 5sinx / 2) - 2 = - 2 (SiNx - 5 / 4) & # 178; + 9 / 8 when SiNx = 1, y has the maximum value ymax = - 2 (1-5 / 4) & # 178; + 9 / 8 = 1; when SiNx = - 1, y has the minimum value ymax = - 2 (- 1-5 / 4) & # 178; + 9 / 8 = 1