cos(п/10)+sin(п/10) преобразовать в сумму

cosπ/10+sinπ/10=√2sin(π/4+π/10)=
√2sin(5π+2π)/20=√2sin7π/20
2)cos(π/2-4π/10)+sinπ/10=
sin4π/10+sinπ/10=
2sin((5π/10):2)*cos(3π/10):2
=2sin(π/4)*cos(3π/20)=
2*(√2/2)*cos(3π/20)=
√2cos(3π/20)