Answer:
79°
Step-by-step explanation:
Use the cosine law:
[tex]BC^2=AC^2+AB^2-2(AC)(AB)\cos A[/tex]
We have
BC = 14, AC = 11 and AB = 11. Substitute:
[tex]14^2=11^2+11^2-2(11)(11)\cos A\\\\196=121+121-242\cos A\\\\196=242-242\cos A\qquad\text{subtract 242 from both sides}\\\\-46=-242\cos A\qquad\text{divide both sides by (-242)}\\\\\cos A=\dfrac{-46}{-242}\\\\\cos A=\dfrac{23}{121}\\\\\cos A\approx0.1901\to m\angle A=79^o\\\\(\text{look at the table on a picture})[/tex]
