Answer:
B, [tex]10^{2} + 5^{2}- 2(10)(5)cos(75)[/tex]
Step-by-step explanation:
Using the law of cosines, which is [tex]c^{2}=a^{2}+b^{2}-2ab cos(C)[/tex], you can simply insert all the values.
c=|u+v|
a= r value of u (10)
b= r value of v (5)
To find C, you simply have to subtract v from u, and then subtract that number from 180 to find the reference angle.
I.E.: ∠135 - ∠30 = ∠105 ↔ 180 - 105 = 75 = C
so, the completed equation would be 10^{2} + 5^{2}- 2(10)(5)cos(75)
