nomor 2 dan 4 tolong diantu kak

2.
sin A = 3/5
cos A = 4/5

tan B = 1/7

x^2 = 1^2 + 7^2 = 1 + 49 = 50
x = 5 akar 2

sin B = 1/(5 akar 2)
cos B = 7/(5 akar 2)

sin (A + B)
= sinA cosB + cosA sinB
= 3/5 × 7/(5 akar 2) + 4/5 × 1/(5 akar 2)
= 21/(25 akar 2) + 4/(25 akar 2)
= 25/(25 akar 2)
= 1/(akar 2)
= 1/2 akar 2

sin 45 = 1/2 akar 2
A+B = 45 = 1/4 phi

4.
10/sin 45 = AC/sin30
AC = 10/(1/akar2) × 1/2
AC = 5 akar2

BC^2 = AB^2 + AC^2 - 2.AB.BC.cos 60
BC^2
= (10 akar2)^2 + (5 akar 2)^2 - 2 . 10akar2 . 5akar2 . 1/2
= 200 + 50 + 100
= 350
BC = 25 akar 14