Which equation could be used to solve for the length of side c, given a = 5, b = 12, and C = 72°?

law of cosines

c^2=(5)^2+(12)^2-2(5)(12)cos72

i had this question before

Step-by-step explanation:

c^2=a^2+b^2-2abcos(c)

c=sqrt(a^2+b^2-2abcos(c))

c=sqrt((5)^2+(12)^2-2(5)(12)cos(72))

c=sqrt(25+144-120cos(72))

c=sqrt(169-120cos(72))

c=sqrt(169-37.08)

c=sqrt(131.92)

c=11.49

step-by-step explanation:

we have

using a graphing tool

see the attached figure

this is a quadratic equation (vertical parabola) open up

the vertex is a > vertex

the domain of the function is all real > interval (-∞,∞)

the range of the function is the > [-6.125,∞)

the function has two x->   and

the function is increasing over the > (0.25,∞)

the function is decreasing over the > (-∞,0.25)