1) sin390° - sin ( - 420°) + ctg (2,25pi)

2) 2cos30°ctg60° - sin3pi/2

1) sin390⁰-sin (-420⁰) + ctg (2π+π/4) =

=sin (360⁰+30⁰) - sin (-360⁰-60⁰) + ctgπ/4=

=sin30⁰ - (-sin60⁰) + 1=sin30⁰+sin60⁰+1=1/2+√3/2+1 = (3+√3) / 2;

2) 2cos30⁰·ctg60⁰-sin3π/2=2· (√3/2) · (√3/3) - (-1) = 2·3/6+1=2;