B1. Draw the set of points $(x, y)$ in a rectangular coordinate system in the plane that satisfy the condition $(x \leq 4) \wedge(y \geq-1) \wedge(y \leq x)$. Calculate the area of the shape that the set of points represents.
B1. We draw half-planes with equations $x \leq 4, y \geq -1$ and $y \leq x$ (the boundaries of the half-planes are lines with equations $x=4, y=-1, y=x$) and mark the intersection of the half-planes - a right triangle. The area of the right triangle is $S=\frac{5 \cdot 5}{2}=\frac{25}{2}$.

![](https://cdn.mathpix.com/cropped/2024_06_07_d6b556bd14f8001ca6fag-13.jpg?height=57&width=1685&top_left_y=1528&top_left_x=228)
Correctly marked triangle................................................................................................................. Calculation of the area of the triangle $S=\frac{5 \cdot 5}{2}=\frac{25}{2} \ldots \ldots \ldots \ldots \ldots \ldots \ldots \ldots \ldots \ldots \ldots \ldots .1+1^{*}$ point

![](https://cdn.mathpix.com/cropped/2024_06_07_d6b556bd14f8001ca6fag-13.jpg?height=468&width=488&top_left_y=1716&top_left_x=224)