Question

Someone please help me with this I can’t get it wrong

Answer 1

Answer:

a = 7

Step-by-step explanation:

a² = b² + c² - 2bc × cos α

a² = 2² + ( 5√3 )² - 2 × 2 × 5√3 × $\frac{\sqrt{3} }{2}$

a² = 49

a = 7

Answer 2

Answer:

a = 7

Step-by-step explanation:

Using the Cosine rule in the triangle

a² = b² + c² - (2bc cosA )

   = 2² + (5$\sqrt{3}$ )² - (2 × 2 × 5$\sqrt{3}$ × cos30° )

  = 4 + 75 - (20$\sqrt{3}$ × $\frac{\sqrt{3} }{2}$ ) ← exact value of cos30°

 = 79 - ( 10 × 3)

 = 79 - 30

 = 49 ( take square root of both sides )

a = $\sqrt{49}$ = 7