ΔABC, AB = AC, AB = 25, BC = 40
Aabc = ?
Rcerc circumscris = R = ?
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Aabc = [tex] \frac{BC*h}{2} [/tex]
h = AD, D∈ BC
AD = [tex] \sqrt{ AB^{2} - ( \frac{BC}{2})^2 } [/tex] = [tex] \sqrt{625 - 400} = \sqrt{225} [/tex] = 15
Aabc = [tex] \frac{40 * 15}{2}[/tex] = 300
R = [tex] \frac{AB * AC * BC}{4Aabc} = \frac{25 * 25 * 40}{4 * 300} [/tex] = 20.833
