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3 years ago

Find the area of the triangle with vertices: q(3,-4,-5), r(4,-1,-4), s(3,-5,-6).

Mathematics

1 answer:

maw [93]3 years ago

3 0

Answer:

(√6)/2 square units

Step-by-step explanation:

The area of a triangle is half the magnitude of the cross product of the vectors representing adjacent sides.

QR = (4-3, -1-(-4), -4-(-5)) = (1, 3, 1)

QS = (3 -3, -5-(-4), -6-(-5)) = (0, -1, -1)

The cross product is the determinant ...

$\text{det}\left|\begin{array}{ccc}i&j&k\\1&3&1\\0&-1&-1\end{array}\right|=-2i+j-k$

The magnitude of this is ...

|QR × QS| = √((-2)² +1² +(-1)²) = √6

The area of the triangle is half this value:

Area = (1/2)√6 . . . . square units

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erica [24]

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Dafna11 [192]

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Two ladders are leaning against a building, forming two similar triangles as shown below. The top of the longer ladder is 28 fee

postnew [5]

Answer:

The length of the longer ladder is 35 ft

Step-by-step explanation:

Please check the attachment for a diagrammatic representation of the problem

We want to calculate the length of the longer ladder ;

We make reference to the diagram

Since the two right triangles formed are similar. the ratios of their sides are equal;

Thus;

20/15 = 28/x + 15

20(x + 15) = 15(28)

20x + 300 = 420

20x = 420-300

20x = 120

x = 120/20

x = 6

So we want to calculate the hypotenuse of a right triangle with other sides 28ft and 21 ft

To do this, we use the Pythagoras’ theorem which states that square of the hypotenuse equals the sum of the squares of the two other sides

Let the hypotenuse be marked x

x^2 = 28^2 + 21^2

x^2 = 1,225

x = √1225

x = 35 ft

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