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prove that sin−1(35)−sin−1(817)=cos−1(8485)
1 Answer
written 5.6 years ago by |
Solution:
Letsin−1(35)=A
∴sinA=35
∴cos2A=1−sin2A
=1−925
=1625
∴cosA=45
sin−1(817)=B∴sinB=817∴cos2B=1−sin2B=1−64289=225289∴cosB=1517∴cos(A−B)=cosAcosB+sinAsinB=45×1517+35×817∴cos(A−B)=8485∴A−B=cos−1(8485)sin−1(35)−sin−1(817)=cos−1(8485)