Question

срочно за три задания даю 100 баллов

Answer 1

$4) CB^2=DB*AB=16*21=336\\CB=4\sqrt{21} \\5)AC=\sqrt{8^2-5^2} =\sqrt{64-25} =\sqrt{39}\\ AD=\sqrt{\sqrt{39} ^{2}-\sqrt{3} ^{2} } =\sqrt{39-3}=\sqrt{36}=6\\ 6) tg30=\frac{4}{DC} \DC=\frac{4}{tg30}=\frac{4\sqrt{3} }{1} =4\sqrt{3}$