tolong jawabb plisssds

a. 180 = 90° + y° + 4y°
180 - 90 = 5y
90 = 5y
y = 90 : 5 = 18°
b. 4y° = 18 x 4 = 72°
sudut CBE = 180° - 72° = 108°
sudut CBE = sudut BDF = 108°

<a+<b+<c = 180°
<a + 45° + 60° = 180
<a = 75°

L = (ab²×sin b×sin c)/2 sin a
L = {(3√2)² × sin 45 × sin 60} / 2 sin 75
L = (18×0,71×0,86) / 2×0,96
L = 10,99 / 1,92
L = 5,72