Question

AB egal cu 5
AC egal cu6
cosA egal cu 3 pe 5
sa se calculeze R?
vreau un raspuns cat mai rapid

Answer 1

$BC^2=AB^2+AC^2-2*AB*AC*cosA$
$BC^2=5^2+6^2-2*5*6* \frac{3}{5}$
$BC^2=25-36+36=25$
$BC=5$
$\frac{BC}{sin A} =2R$
$sinA= \frac{1}{cosA} = \frac{5}{3}$
$\frac{5}{ \frac{5}{3} } =2R =\ \textgreater \ R= \frac{5*3}{5*2} = \frac{3}{2}$
$R=1,5$