Question

geometry
angles and trigonometric ratios
which of the following is equivalent to sin19°?
11 of 11 question
tan19°
sin71°
cos19°
cos71°

Explanation:

Step1: Use co - function identity

The co - function identity is \(\sin\theta=\cos(90^{\circ}-\theta)\).

Step2: Substitute \(\theta = 19^{\circ}\)

When \(\theta = 19^{\circ}\), we have \(\sin19^{\circ}=\cos(90^{\circ}-19^{\circ})\).
Calculate \(90^{\circ}-19^{\circ}=71^{\circ}\). So \(\sin19^{\circ}=\cos71^{\circ}\).

Answer:

\(\cos71^{\circ}\)