(Originais Teachy 2023) - Question Easy of Mathematics

The image presented in the figure is a black and white copy of the square canvas titled The Fish, by Marcos Pinto, which was placed on a wall for exhibition and fixed at points A and B (figure 1). Due to a problem in fixing one of the points, the canvas detached and rotated close to the wall. After the rotation, it was positioned as illustrated in figure 2, forming a 45° angle with the horizon line. Figure 1 Figure 2 To put the canvas back in its original position, it should be rotated, close to the wall, at the smallest possible angle less than 360°. The way to put the canvas back in the original position, following what was established, is by rotating it at an angle of

In a large engineering system, a building is being designed and energy efficiency is a major concern. To ensure the efficiency of heating and cooling, the air conditioning system must be sized according to the specific needs of the building. The engineer in charge of the project must solve a system of linear equations to determine the ideal operating temperatures. Let the following be the system of equations that models the thermal behavior of the building: 2x + y + 3z = 10, 4x - 6y + 8z = 5, 3x + 7y + 5z = 18. The engineer must rewrite this system of equations in the matrix form Ax = b, where A is the matrix of coefficients, x is the vector of unknowns, and b is the vector of constant terms.

In a civil engineering project, an architect needs to divide a rectangular plot of land into two equal parts for the construction of two semi-detached houses. The coordinates of the vertices of the land on the Cartesian plane are A(0, 0), B(30, 0), C(30, 20), and D(0, 20). Using concepts of analytic geometry, determine the coordinates of the point that represents the midpoint of side CD of the land, which will be the dividing point between the two new properties. Then, verify if the obtained midpoint point is indeed on segment CD, ensuring the accuracy of the project. Explain the reasoning used to determine the coordinates and to verify the positioning of the midpoint on the land.

In a school presentation, eight friends, including Carlos, Timóteo, and Joana, line up. Calculate the number of different ways this line of friends can be formed so that Carlos, Timóteo, and Joana always stay together: