Question Video: Finding the Distance between a Point and a Plane | Nagwa Question Video: Finding the Distance between a Point and a Plane | Nagwa

Question Video: Finding the Distance between a Point and a Plane Mathematics • Third Year of Secondary School

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Find the distance between the point (2, 8, 3) and the plane (𝑥 − 2) + 2(𝑦 −1) + 5(𝑧 − 4) = 0 to the nearest two decimal places.

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Video Transcript

Find the distance between the point two, eight, three and the plane 𝑥 minus two plus two times 𝑦 minus one plus five times 𝑧 minus four equals zero to the nearest two decimal places.

In this question, we want to determine the distance between a given point and plane to the nearest two decimal places. To do this, we can start by recalling that when we say the distance between a point and a plane, we mean the perpendicular distance since it is the shortest distance between the two objects. We can find the distance between the point 𝑥 sub one, 𝑦 sub one, 𝑧 sub one and the plane 𝑎𝑥 plus 𝑏𝑦 plus 𝑐𝑧 plus 𝑑 equals zero using the formula the absolute value of 𝑎𝑥 sub one plus 𝑏𝑦 sub one plus 𝑐𝑧 sub one plus 𝑑 all divided by the square root of 𝑎 squared plus 𝑏 squared plus 𝑐 squared.

We are given the coordinates of the point in the question. These coordinates tell us the values of 𝑥 sub one, 𝑦 sub one, and 𝑧 sub one. However, we are not given the equation of the plane in the correct form. We can rewrite this equation in the correct form by expanding and simplifying. First, we distribute each factor over the parentheses to obtain 𝑥 minus two plus two 𝑦 minus two plus five 𝑧 minus 20 is equal to zero. Second, we evaluate the constant terms in the equation to get 𝑥 plus two 𝑦 plus five 𝑧 minus 24 equals zero.

Now, the equation of the plane is in the correct form. So the coefficients of 𝑥, 𝑦, and 𝑧 will tell us the values of 𝑎, 𝑏, and 𝑐, and the constant tells us the value of 𝑑. We have 𝑎 equals one, 𝑏 equals two, 𝑐 equals five, and 𝑑 equals negative 24.

We can now find the distance between the point and the plane by substituting these values into the formula and evaluating. We get that the distance is the absolute value of one times two plus two times eight plus five times three minus 24 all over the square root of one squared plus two squared plus five squared. Evaluating this expression gives us nine divided by the square root of 30. We can evaluate this radical using a calculator to obtain 1.643, and this expansion continues. Rounding this to two decimal places gives us that the distance between the point and the plane is 1.64 to the nearest two decimal places.

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