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Angle B = 106.6 degrees

Step-by-step explanation:

b^2= a^2+c^2-2*a*c*cosB

9*9 = 4*4 + 7*7 - 2*7*4*cosB

81= 16+49-56cosB           Subtract 16 and 49 from both sides

16= -56cosB           Divide by -56 on both sides.

cosB= -16/56         Take the arccosine of both sides

B=arccos(-16/56)                    

B= 106.6

B. 106.6

Step-by-step explanation:

To solve for angle B, we can use the law of cosines.

Recall that the law of cosines states

When this is solved for angle B, we get

In this triangle,

Now, we can plug these numbers into our equation and then simplify to get B.

step-by-step explanation:

first, eliminate the parenthesis:

3

x

+

2

−

4

x

second, group like terms:

3

x

−

4

x

+

2

third, combine like terms:

(

3

−

4

)

x

+

2

→

−

1

x

+

2

→

−

x

+

2

10000

step-by-step explanation: divide by 2,