sin15x + cos15x
= sin15xcos(π/4) + cos15xsin(π/4)
= sin(π/4 + 15x) = 0
故 π/4 + 15x = kπ (k为整数)
x = π/20 + kπ/15 (k为整数)
x的最小正数解就是π/20
sin15x + cos15x
= sin15xcos(π/4) + cos15xsin(π/4)
= sin(π/4 + 15x) = 0
故 π/4 + 15x = kπ (k为整数)
x = π/20 + kπ/15 (k为整数)
x的最小正数解就是π/20