Question

Cos13 tita + cos 9 tita.

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Answer 1

Hello Friend..❤️❤️

The answer of u r question is..✌️✌️

Cos 13 tita + cos 9 tita

So,we have to use the formula

Cos C + cos D = 2 cos(c+D/2) cos (C-D/2)


$= 2cos( \frac{130 + 90}{2} ) \: cos( \frac{130 - 9}{2} )$

$= 2cos \: ( \frac{220}{2} )cos( \frac{40}{2} )$

So,

The final answer is..

$= 2cos11 tita \: cos2tita$

Thank you..⭐️⭐️⭐️

Answer 2

AHOy!

Refer to the attachment