Answer:
Apply Pythagorean theorem:
AB^2 = AC^2 + BC^2
<=>AB^2 = 5^2 + 12^2
<=>AB^2 = 25 + 144
<=> AB^2 = 169 = 13^2
<=> AB = 13
Apply sine and cosine theorem:
sinA = BC/AB = 12/13
cosA = AC/AB = 5/13
tanA = sinA/cosA = (12/13)/(5/13) = 12/5
Hope this helps!
:)
