The exact length of a which is equivalent to BC is 7units
Cosine rule
A triangle is a shape with 3 sides and angles. In order to determine the sides BC, we will use the cosine rule
c² = a² + b² - 2abcosC
Given the following parameters
b = 2
c = 5√3
theta = 30 degrees
Substitute
c² = 2² + (5√3)² - 2abcos30
c² = 4 + 75 - 2(2)(5√3)*√3/2
c² = 79 - 30
c² = 49
c = 7 units
Hence the exact length of a which is equivalent to BC is 7units
Learn more on triangles here: https://brainly.com/question/17335144
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