Question

Решите пожалуйста по формулам

Answer 1

1. S = a * b = 6.7 * 2.5 = 16.75

2. S = a * h = 3.2 * 6 = 19.2

3. $S_{ABCD}=S_{AOB}+S_{BOC}+S_{AOD}+S_{COD}=\frac{1}{2}*AO*BO+\frac{1}{2}*OC*BO+\frac{1}{2}*AO*OD+\frac{1}{2}*CO*OD=\frac{1}{2}*(AO*BO+OC*BO+AO*OD+OC*OD)=\frac{1}{2}*(BO*(AO+OC)+OD(AO+OC))=\frac{1}{2}*(AO+OC)(BO+OD)=\frac{1}{2}*AC*BD=\frac{1}{2}*6*8=24$

4. $S=\frac{a+b}{2}*h=\frac{6+18}{2}*2.5=30$

5. $S=a^{2}=1.2^{2}=1.44$

6. $S=\frac{a*b}{2}=\frac{6*2.1}{2}=6.3$

7. $S=\frac{\sqrt{3}}{4}*a^{2}=\frac{\sqrt{3}}{4}*6^{2}=9\sqrt{3}$

8. $S=\frac{1}{2}*a*h=\frac{1}{2}*4*2.5=5$

9. По формуле Герона

$S=\sqrt{p(p-a)(p-b)(p-c)}\\p=\frac{a+b+c}{2}=\frac{3+4+5}{2}=6\\S=\sqrt{6(6-3)(6-4)(6-5)}=\sqrt{6*3*2*1}=6$