Answer:
Option (3)
Step-by-step explanation:
By applying cosine rule in the triangle ABC,
BC² = AC² + AB² - 2(AC)(AB)cosA
5² = 3² + 7²- 2(3)(7)cosA
25 = 9 + 49 - 42cos(A)
25 = 58 - 42cos(A)
cos(A) = 
A = 
A = 38.21°
A ≈ 38°
Option (3) will be the correct option.
Answer:
what you mean by 1 `hour?
Step-by-step explanation:
Can't answer 1-6 cause I have no idea what you need
7) A triangle with two congruent sides is isosceles.
8)
and 
9) 
10) 
11) 
12) isosceles triangle
D (-1,9) i did it in calcukator