Question

Помогите с номером 12 по тригонометрии, пожалуйста.
Не понимаю как его решить.

Answer 1

[2sinπ/9-5sin(π-π/9)]/[2cos(2π-7π/18)-3cos7π/18]=
=(2sinπ/9-5sinπ/9)/(2cos7π/18-3cos7π/18)=(-3sinπ/9)/(-cos7π/18)=
=(3sinπ/9)/(cos(π/2-π/9))=(3sinπ/9)/sinπ/9)=3

Answer 2

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