Question 976917
This a triangle I take it.
Side a = 6cm 
Side b = 4cm
Side c = 7cm 
Find angle B
Using Cosine Rule
Cos B = (a^2 + c^2 - b^2)/ 2ac
Cos B = (6^2 + 7^2 - 4^2)/ 2 x 6 x 7
Cos B = (36 + 49 - 16)/ 84
Cos B = 69/84
Cos B = 0.8214
Angle B = 34.77 degrees (2 decimal places)
Hope this helps :-).