Question

ex 11 rapid va rog dau coroana​

Answer 1

AB=AC=10 cm

AD=8 cm

• Aplicam Pitagora in ΔADB dr in D

AB²=AD²+BD²

100=64+BD²

BD=√36

BD=6 cm⇒ BC=12 cm

P=AB+AC+BC=10+10+12=32 cm

Teorema sinusului:

$\frac{b}{sinB}=2R\\\\ \frac{AC}{sinB} =2R\\\\\frac{10}{\frac{AD}{AB} }=2R\\\\ \frac{10}{\frac{8}{10} } =2R\\\\100=16R\\R=6,25 cm$

sau

$A=\frac{abc}{4R} \\\\A=\frac{AD\times BC}{2} =\frac{8\times 12}{2} =48cm^2\\\\48=\frac{10\times10\times12}{4R} \\\\\\R=6,25cm$