Prove that: \ sin 50^0+sin 10^0=cos 20^0...

Prove that: `\ sin 50^0+sin 10^0=cos 20^0`

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We have to proof,
`sin(50^o)+sin(10^o)=cos(20^o)`
Let L.H.S.=`sin(50^o)+sin(10^o)`
As we know the formula `sin(C^o)+sin(D^o)=2((sin(C^o)+(D^o))/2)cos(C^o−D^o)/2`
then, L.H.S=`sin(50^o)+sin(10^o)`
L.H.S= `2(sin((50^o)+(10^o))/2)(cos(50 ^o−10^o)/2)`
L.H.S=`2sin30^ocos20^o`
...

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