Question

sva rog frumos partea aIIIa​

Answer 1

2)

m(∢BAD) + m(∢ADC) = 180°

m(∢ADC) = 180° - 40° = 140°

3)

A (ABCD) = AB×AD×sin(∢BAD) = 2×4×sin 60° =

$= 8 \times \dfrac{ \sqrt{3} }{2} = 4 \sqrt{3} \ {cm}^{2}$

4)

$\cos \measuredangle ACB = \dfrac{AC}{BC}$

$AC = BC \cdot \cos {30}^{0} = 10 \cdot \dfrac{ \sqrt{3} }{2} = 5 \sqrt{3} \ cm$