Question

In triangle ABC, what is the m

Answer 1

`\boxed {38^(o)}`

Explanation:

Applying Law of Cosines :

⇒ a² = b² + c² - 2bc(cos A)

⇒ 14² = 22.8² + 18² - 2(22.8)(18)(cos A)

⇒ 820.8(cos A) = 519.84 + 324 - 196

⇒ 820.8(cos A) = 647.84

⇒ cos A = 647.84/820.8

⇒ cos A = 0.789278752

⇒ m ∠A = cos⁻¹ (0.789278752)

⇒ m ∠A = 37.88 ≈ 38°

Answer 2

Answer: 38°

Using cosine rule,

a² = b² + c² -2bc cos(A)

Insert values from diagram

14² = 18² + 22.8² - 2(18)(22.8) cos(A)

196 = 324 + 519.84 - 820.8 cos(A)

-820.8 cos(A) = 196 - 324 - 519.84

-820.8 cos(A) = -647.84

cos(A) = -647.84/-820.8

A = cos^{-1} (-647.84/-820.8)

A = 37.88°

A ≈ 38°