Correct Answer - Option 2 : -sin α
Concept:
The table below shows the sign of trigonometric ratios in different quadrants:
|
T – Ratio’s
|
Quadrant I
|
Quadrant II
|
Quadrant III
|
Quadrant IV
|
|
Sin
|
+
|
+
|
-
|
-
|
|
Cos
|
+
|
-
|
-
|
+
|
|
Cosec
|
+
|
+
|
-
|
-
|
|
Sec
|
+
|
-
|
-
|
+
|
|
Tan
|
+
|
-
|
+
|
-
|
|
Cot
|
+
|
-
|
+
|
-
|
Calculation:
(π + θ) lies in 3rd quadrant
As we know sin θ gives negative value in 3rd quadrant
Therefore, sin (π + α) = -sin α
