Question

tam giác ABC có các góc A=75, B=45. tính tỉ số AB/AC

Answer 1

Áp dụng đl tổng 3 góc trong tam giác:

\(\Rightarrow\widehat{C}=180^o-75^o-45^o=60^o\)

Ta có:

\(\dfrac{AB}{sinC}=\dfrac{AC}{sinB}\\ \Rightarrow\dfrac{AB}{AC}=\dfrac{sinC}{sinB}=\dfrac{\sqrt{6}}{2}\)

$HaNa$

Answer 2

Mà: \(\widehat{C}=180^o-75^o-45^o=60^o\)

Ta có:

\(\dfrac{AC}{sinB}=\dfrac{AB}{sinC}\)

\(\Rightarrow\dfrac{AB}{AC}=\dfrac{sinC}{sinB}\)

\(\Rightarrow\dfrac{AB}{AC}=\dfrac{sin60^o}{sin45^o}\)

\(\Rightarrow\dfrac{AB}{AC}=\dfrac{\dfrac{\sqrt{3}}{2}}{\dfrac{\sqrt{2}}{2}}\)

\(\Rightarrow\dfrac{AB}{AC}=\dfrac{\sqrt{3}}{\sqrt{2}}\)

\(\Rightarrow\dfrac{AB}{AC}=\dfrac{\sqrt{6}}{2}\)