1. A farm has a flat triangular grassland. If the grassland is divided into four parts, statistics show that the grassland in the west can graze 5 sheep, the grassland in the south can graze 10 sheep, and the grassland in the east can graze 8 sheep. How many sheep can the grassland in the north graze?

Extend CO to AB to d and BO to AC to e.

The idea is: take the breeding area as the area value.

1. Use triangle area ratio.

BOD area of triangle: 0.5*BO*BD*sinABO=5.

ABE area of triangle: 0.5*BA*BE*sinABO=(x+5), let the required area be x;

The ratio of the two areas is: 5: (x+5) = Bo * BD: Be * AB;

Let the height of triangle ABC to BC be h4, that of BCO to BC be h 1, that of BEC to BC be h2, and that of BDC to BC be H3;

According to the area ratio of the triangle: BDC BEC BCD, we can get: h1:H2: H3: H4 =10:18:15: (x+23).

Bo: Be = h1:H2 =10:18;

BD:AB= 15:(x+23)

Substituting the area ratio of the first two triangles for simplification, we can get that the value of x is 22.

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The thinking should be correct. Do the math yourself.