The value of the expression: sin21° + sin211° + sin221° + sin231° + sin241° + sin245° + sin249° + sin259° + sin269° + sin279° + sin289° is?
A. 0
B. $${\text{5}}\frac{1}{2}$$
C. $${\text{4}}\frac{1}{2}$$
D. 5
Answer: Option B
Solution(By Examveda Team)
sin21° + sin211° + sin221° + sin231° + sin241° + sin245° + sin249° + sin259° + sin269° + sin279° + sin289°= (sin21° + sin289°) + (sin211° + sin279°) + (sin221° + sin269°) + (sin231° + sin259°) + (sin241° + sin249°) + sin245°
= 1 + 1 + 1 + 1 + 1 + $$\frac{1}{2}$$ [sin2A + sin2B = 1. If, A + B = 90°]
= $$5\frac{1}{2}$$
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