Question

What’s the correct answer

Answer 1

Answer:

79°

Step-by-step explanation:

Using the cosine rule in ΔABC

cosA = $\frac{b^2+c^2-a^2}{2bc}$

with a = 14, b = 11, c = 11, then

cosA = $\frac{11^2+11^2-14^2}{2(11)(11)}$ = $\frac{46}{242}$

A = $cos^{-1}$($\frac{46}{242}$) ≈ 79°

Answer 2

Answer:

(A) 79°

Step-by-step explanation:

We can use law of cosine.

c²=a²+b²-2ab*cos(α)

14²=11²+11²-2*11*11*cos(A)

14²=2*11²-2*11²cos(A)

14²-2*11²=-2*11²cos(A)

-46= - 2*(121)*cos(A)

cos(A)= 46/242

arccos(46/242)=79°