सिद्ध कीजिए की:
` cos 10^(@) - cos 50^(@) =sin 20^(@) `

(2cos40^(@)-cos20^(@))/(sin20^(@))

(2cos40^(@)-cos20^(@))/(sin20^(@))

(2cos40^(@)-cos20^(@))/(sin20^(@))=?

sin 40^(@) - cos 50^(@)= _________

Prove that (i) sin 70^(@) cos 10^(@) -cos 70^(@) sin 10^(@) =(sqrt(3))/(2) (ii) cos 50^(@) cos 10^(@) -sin 50^(@) sin 10^(@) =(1)/(2) (ii) cos 80^(@) cos 20^(@) + sin 80^(@) sin 20^(@) =(1)/(2) (iv) sin 36^(@) cos 9^(@) + cos 36^(@) sin 9^(@) =(1)/(sqrt(3))

The value of cos ^(2) 10^(@) - cos 10^(@) cos 50^(@) + cos ^(2) 50^(@) is equal to

(cos 10^(@) - sin 10^(@))/(cos 10^(@) + sin 10^(@)) is