Question

giúp mik vs ạ. Cảm ơn mn

 

Answer 1

a, Ta có : \(AC^2=AB^2+BC^2=40^2+42^2=3364\Rightarrow AC=58\)cm * đúng *

Vậy tam giác ABC vuông tại B 

b, \(\sin A=\dfrac{BC}{AC}=\dfrac{42}{58}=\dfrac{21}{29}\)

\(\cos A=\dfrac{AB}{AC}=\dfrac{40}{58}=\dfrac{20}{29}\)

\(\tan A=\dfrac{BC}{AB}=\dfrac{42}{40}=\dfrac{21}{20}\)

\(\cot aA=\dfrac{AB}{BC}=\dfrac{40}{42}=\dfrac{20}{21}\)