Cos(B+15°)-cosB cos15°//sinB×cos15°=

Question

Cos(B+15°)-cosB cos15°//sinB×cos15°=

Answer 1

Cos(b+15°)=cosb*cos15°-sinb*sin15°
cosb*cos15°-sinb*sin15°-cosb*cos15°/sinb*cos15°=-sinb*sin15°/sinb*cos15°=-sin15°/cos15°=-tg15°