sin^2 45 + 2cos^2 30 =

pecah saja menjadi
sin(45) x sin(45) + 2 x cos(30) x cos (30)

sin 45 itu [tex] \frac{ \sqrt{2} }{2} [/tex], sedangkan cos 30=  [tex] \frac{ \sqrt{3} }{2} [/tex]

sehingga menjadi:
[tex] \frac{ \sqrt{2} }{2} .\frac{ \sqrt{2} }{2} +2\frac{ \sqrt{3} }{2} .\frac{ \sqrt{3} }{2} [/tex]
[tex] \frac{2}{4} + \frac{6}{4} =2[/tex]

sin^2 45 + 2cos^2 30

sin^2 45
= (sin 45)^2
= ( √2/2 ) ^2
= (2/4)
= 1/2

cos^2 30
= (cos 30)^2
= (√3/2)^2
= 3/4

1/2 + 2 x 3/4
= 1/2 + 6/4
= 2/4 + 6/4
= 8/4
= 2