If cosec(a-b) = 2/3 and sec(a+b) = 2, find the least positive values of a and b.
⇒ sin (a – b) = sin 60° = sin 120°
⇒ a – b = 120° .......... (i)
Adding (i) and (ii),
a – b + a + b = 120° + 315°
⇒ 2a = 435°
⇒ a = 217.5°
⇒ b = 315° – 217.5° [ from equation (ii) ].
⇒ b = 97.5°
∴ a = 217.5° and b = 97.5°