Any angle trigonometry function example
Question:
Given: sin (9pi/2 + a) = 1/5. Find the value of cos a.
Solution:
- sin (9pi/2 + a)
- = sin [(8pi + pi)/2 + a]
- = sin (4pi + pi/2 + a)
- = sin (pi/2 + a)
- = cos a
- = 1/5
Because sin (9pi/2 + a) = 1/5 and sin (9pi/2 + a) = cos a. So, cos a = 1/5. Watch the video for more details.