Question

Giải tam giác vuông ABC ( A=90°), biết; a) BC =6cm ; B= 50° b) AB =5cm; AC= 7cm

Answer 1

\(a,\widehat{C}=90^0-\widehat{B}=40^0\\ AB=\cos B\cdot BC\approx3,9\left(cm\right)\\ AC=\sin B\cdot BC\approx4,6\left(cm\right)\\ b,BC=\sqrt{AB^2+AC^2}=\sqrt{74}\left(cm\right)\\ \sin B=\dfrac{AC}{BC}=\dfrac{7\sqrt{74}}{74}\approx\sin54^0\\ \Rightarrow\widehat{B}\approx54^0\\ \Rightarrow\widehat{C}=90^0-\widehat{B}\approx36^0\)