Answer:
-¹²/₅
Explanation:
Let cos a = -⁵/₁₃
Then tan a = sin a/cos a
= [√(1 - cos²a)]/cos a
= {√[1 - (-⁵/₁₃)²]}/(-⁵/₁₃)
= -[√(1 - ²⁵/₁₆₉)] × ¹³/₅
= -[(√(¹⁴⁴/₁₆₉ )] × ¹³/₅
= -¹²/₁₃ × ¹³/₅
= -¹²/₅
tan(arccos (-⁵/₁₃)) = -¹²/₅
The diagram shows the 2nd quadrant of a circle with radius 13, cos a = -⁵/₁₃, and tan a = ¹²/₍₋₅₎ = -¹²/₅.