siku siku di C. AC=1cm. BC = akar3 besar sudut A adalah.. A. 120° b. 75° c.60° d.45° e.30°

AC = 1
BC = √3
AB = √1^2 + (√3)^2
= √1 + 3
= √4
= 2

Aturan cosinus
BC^2 = AC^2 + AB^2 - 2.AC.AB. cos A
(√3)^2 = 1^2 + 2^2 - 2.1.2 cos A
3 = 1 + 4 - 4cosA
4 cos A = 5 - 3
cos A = 2/4
cos A = 1/2
cos A = cos 60
A = 60 derajat.

siku-siku di C
AC = 1 cm
BC = akar 3
AB = akar [AC^2 + BC^2]
= akar [1^2 + (akar 3)^2]
= akar [1 + 3]
= akar 4
= 2 cm
BC / sin a = AB / sin c
(akar 3) / sin a = 2 / sin 90°
(akar 3) / sin a = 2 / 1
(akar 3) / sin a = 2
sin a = (akar 3) / 2
sin a = 1/2 akar 3
a = arc sin 1/2 akar 3
a = 60°
Jadi besar sudut A adalah 60° (C)