1 8-sinf geom yangi. 1-8-bet. 2015(boshi). p65

S = 10 AD = 5 V100 - 25 = 5 -V75 = 25/3


yoki
S = V25 • 75 ^л/1875 - 43,3 . Bularning hammasi so‘z bilan tushuntirilgan.
Savol, masala va topshiriqlar

389. 
     1) Ustunning tik ekani qanday tekshiriladi?
     

2. 
   Tomonlari 5, 6 va 9 birlikka teng bo‘lgan uchburchakning yuzini toping.
   

389. 
     Teng yonli trapetsiyaning diagonali 25 sm ga, balandligi esa 15 sm ga teng. Trapetsiyaning yuzini toping.
     
390. 
     ABCD kvadratning tomoni 12 sm ga teng. Uning AB tomonida P nuqta shunday belgilanganki, unda PC = 13 sm. APCD to‘rtburchakning yuzini toping.
     
391. 
     To‘g‘ri to‘rtburchakning perimetri 62 sm, diagonallarining kesishish nuqtasidan tomonlardan birigacha bo‘lgan masofa esa 12 sm ga teng. Shu to‘g‘ri to‘rtburchakning diagonalini toping.
     
392. 
     ABCD to‘g‘ri to‘rtburchakning BC tomonida P nuqta shunday belgi­langanki, unda AP = 15 sm, BA = 12 sm, PC = 6 sm. APCD to‘rtbur- chakning yuzini toping.
     
393. 
     Uchburchakning balandligi 36 sm, yon tomoni 85 sm va 60 sm. Shu uchburchakning yuzini toping (ikki holni ko‘rib chiqing).
     
394. 
     To‘g‘ri to‘rtburchakning tomonlari 8 sm va 15 sm. Uning diagonalini toping.
     
395. 
     Rombning diagonallari 14 sm va 48 sm. Rombning perimetrini va paral­lel tomonlar orasidagi masofani toping.
     

3.