Skip to main content

Limit of (sin x)^(tan x) as x→π

Short answer

Form 0^0 (limit from the left). Let L = lim, then ln L = lim tan x ln(sin x) = lim ln(sin x)/cot x. L'Hospital gives ln L = -lim cos x sin x = 0, so L = 1.

Evaluate lim_{x→π} (sin x)^(tan x).

Let L = lim_{x→π} (sin x)^(tan x). As x → π, sin x → 0 and tan x → 0: form 0⁰. (sin x is positive only for x < π, so the limit is taken as x → π⁻.)

ln L = lim tan x · ln(sin x) = lim ln(sin x)/cot x (form ∞/∞)

Apply L'Hospital's rule:

ln L = lim (cot x)/(−cosec²x)
     = −lim cos x · sin x       (since cot x / cosec²x = cos x sin x)
     = −(−1)(0) = 0

Answer: L = e⁰ = 1.

✓ Answer checked by Claude Opus 5.5 (high effort)

All Mathematics I chapter 1 questions →