High School

Solve triangle ABC if \( a = 66 \), \( b = 25 \), and \( c = 45 \). Round angle measures to the nearest degree.

Answer :

The angles of triangle ABC are approximately 23°, 33°, and 26°.

Given:

a = 66

b = 25

c = 45

Using the Law of Cosines:

[tex]c^2[/tex] = [tex]a^2[/tex] + [tex]b^2[/tex] - 2ab cos(C)

45^2 = 66^2 + 25^2 - 2(66)(25) cos(C)

2025 = 4356 + 625 - 3300 cos(C)

2025 = 4981 - 3300 cos(C)

-2956 = -3300 cos(C)

cos(C) = 0.8957

C = 26°

Using the Law of Sines:

a/sin(A) = b/sin(B) = c/sin(C)

66/sin(A) = 25/sin(B) = 45/sin(26°)

sin(A) = 66 * sin(26°) / 45 = 0.3846

A = 23°

Using the Law of Sines again:

b/sin(B) = c/sin(C)

25/sin(B) = 45/sin(26°)

sin(B) = 25 * sin(26°) / 45 = 0.5556

B = 33°

Therefore, the angles of triangle ABC are approximately 23°, 33°, and 26°.