Correct Answer - Option 1 : 3/2
Given:
Side AB = 7 cm
BC = 8 cm
AC = 9 cm
Identity used:
If the sides of triangle ABC are
AB = c
BC = a
AC = b
Cosine rule;
Cos C = (a2 + b2 - c2)/2ab
Sec θ = 1/cos θ
Calculation:
In triangle ABC;
Cos C = (82 + 92 - 72)/(2 × 8 × 9)
⇒ (64 + 81 - 49)/144
⇒ 96/144 = 2/3
∴ The value of Sec C = 3/2