Angle bisector theorem for computing an angle

Trianlge ABC has $AB=33,AC=88,BC=77.$. Point D lies on BC with $BD=21.$. Compute $\mathrm{\angle}BAD.$.

Trianlge ABC has $AB=33,AC=88,BC=77.$. Point D lies on BC with $BD=21.$. Compute $\mathrm{\angle}BAD.$.