Lúcia was given this problem:A 15-meter ladder is leaning against a wall. The distance y(t) between the top of the ladder and the ground is decreasing at a rate of 6 meters per minute. At a certain instant t0, the bottom of the ladder is a distance x(t0) of 12 meters from the wall. What is the rate of change of the angle θ(t) between the ground and the ladder at that instant?Which equation should Lúcia use to solve the problem?Choose 1 answer:(A) sin[θ(t)]=15y(t)(B) θ(t)=2x(t)⋅y(t)(C) θ(t)+x(t)+y(t)=180(D) [θ(t)]2=[x(t)]2+[y(t)]2
Q. Lúcia was given this problem:A 15-meter ladder is leaning against a wall. The distance y(t) between the top of the ladder and the ground is decreasing at a rate of 6 meters per minute. At a certain instant t0, the bottom of the ladder is a distance x(t0) of 12 meters from the wall. What is the rate of change of the angle θ(t) between the ground and the ladder at that instant?Which equation should Lúcia use to solve the problem?Choose 1 answer:(A) sin[θ(t)]=15y(t)(B) θ(t)=2x(t)⋅y(t)(C) θ(t)+x(t)+y(t)=180(D) [θ(t)]2=[x(t)]2+[y(t)]2
Identify Trigonometric Functions: Lúcia needs to find an equation that relates the angle θ(t) with the sides of the right triangle formed by the ladder, the wall, and the ground. Since we are dealing with a right triangle and we are interested in the angle, trigonometric functions are the most appropriate to use.
Correct Equation Selection: Option (A) sin[θ(t)]=15y(t) is the correct equation to use because it relates the angle θ(t) with the opposite side y(t) and the hypotenuse of the triangle, which is the length of the ladder (15 meters). This equation is derived from the definition of the sine function in a right triangle.
Incorrect Equation (B): Option (B) θ(t)=2x(t)⋅y(t) is not a trigonometric relationship and does not represent any known relationship between the sides of a triangle and an angle.
Incorrect Equation (C): Option (C) θ(t)+x(t)+y(t)=180 is incorrect because it seems to suggest that the angle and the lengths of the sides of the triangle add up to 180, which is not true. In a triangle, it is the angles that add up to 180 degrees, not the sides and an angle.
Incorrect Equation (D): Option (D) [θ(t)]2=[x(t)]2+[y(t)]2 is incorrect because it resembles the Pythagorean theorem, which relates the squares of the sides of a right triangle, not an angle and the sides.
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