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how to solve? (1 Viewer)

kev-kun

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Draw two separate triangles for sin(a) and sin(b). Use pythagoras to find the last side. Expand the sin(a+b) and after that its just a matter of substitution.
 

Squar3root

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draw a triangle such that sina = 4/5 and another triangle such that sinb = 5/13


sin(a + b) = sin a cos b + sin b cos a

now read the values from the triangles and sub them in above

my answer was 63/65
 

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