Question

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

Answer 1

a = 7

Explanation:

a² = b² + c² - 2bc × cos α

a² = 2² + ( 5√3 )² - 2 × 2 × 5√3 ×
`(√(3) )/(2)`

a² = 49

a = 7

Answer 2

a = 7

Explanation:

Using the Cosine rule in the triangle

a² = b² + c² - (2bc cosA )

= 2² + (5
`√(3)` )² - (2 × 2 × 5
`√(3)` × cos30° )

= 4 + 75 - (20
`√(3)` ×
`(√(3) )/(2)` ) ← exact value of cos30°

= 79 - ( 10 × 3)

= 79 - 30

= 49 ( take square root of both sides )

a =
`√(49)` = 7