<h3>
Answer: 26.2</h3>
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Explanation:
Let's make A = 105 the given angle. The side opposite this is 'a'
The two given sides are b = 18 and c = 15
Use the law of cosines to find side 'a'
a^2 = b^2 + c^2 - 2*b*c*cos(A)
x^2 = 18^2 + 15^2 - 2*18*15*cos(105)
x^2 = 324 + 225 - 540*cos(105)
x^2 = 324 + 225 - 540*(-0.258819045102521
)
x^2 = 324 + 225 + 139.762284355361
x^2 = 688.762284355361
x = sqrt(688.762284355361)
x = 26.2442809837755
x = 26.2
Side note: make sure your calculator is in degree mode.