sin 0=0 ⇒sin²0=sin 0²=0
sin²30=(sin30)²=(1/2)²=1/4
sin²45=(sin45)²=(√2/2)²=2/4=1/2
sin²60=(sin60)²=(√3/2)²=3/4
sin²90=(sin90)²=1²=1
sin²75=(sin75)²
Facem suma pentru a obtine 75
sin(30+45)=sin30*cos45+sin45*cos30
sin(30+45)=1/2*√2/2+√2/2*√3/2
sin(30+45)=√2/4+√6/4
sin(30+45)=(√2+√6)/4
sin²75=[(√2+√6)/4]²=(√2+√6)²/4²=(2+2*√2*√6+6)/16=(8+2√12)/16=(8+4√3)/16
Factor comun⇒[4(2+√3)]/16
Simplificam 4 cu 16
(2+√3)/4
Sin²15=(sin15)²
sin15 il scriem ca sin(45-30)\
sin(a-b)=sina*sinb-cosb*cosa
Faci calculele necesare
Acum iti ramane doar de adunat toate valorile
