2cos(1200t-62°)+1.2cos(1200t+28°)
=2sin(1200t-62°+90°)+
1.2cos(1200t+28°)
=2sin(1200t+28°)+1.2cos(1200t+28°)
=√[2^2+(6/5)^2]sin(1200t+28°+a)
=2√34/5sin(1200t+28°+a)
a=arcsin(3√34/34)
2cos(1200t-62°)+1.2cos(1200t+28°)
=2sin(1200t-62°+90°)+
1.2cos(1200t+28°)
=2sin(1200t+28°)+1.2cos(1200t+28°)
=√[2^2+(6/5)^2]sin(1200t+28°+a)
=2√34/5sin(1200t+28°+a)
a=arcsin(3√34/34)