Trigonometry

Question

Show that 2 tan20° + 4 tan40° + 8 tan 80° = 9(cot10° - tan10°).

 

 

Thank you :)

Answer 1

Put values

 

tan 20 = 0.3639, tan 40 = 0.8390, tan 80 = 5.6713, cot 10 = 5.6713, tan 10 =0.1763

(2 x 0.3696) + 4(0.8390) + 8(5.6713) = 49.4656

9( 5.6713 - 0.1763) =49.455

Pretty close :)