Simplify: 5 -3 • 5 5 25 8 25 -15 5 -3 5 2

to estimate the height of the jin mao tower in shanghai , a tourist sights the top of the tower form a mirror that is 86.7 meter

Ray Of Light [21]

Answer:

The height of the tower = 420.48 meters

Step-by-step explanation:

For better understanding of the solution, see the figure attached below :

Let the height of the tower be x meters

Now, using the laws of reflection : angle of reflection = angle of incidence

Also, both the tower and the tourist are standing parallel to each other

⇒ ∠A = ∠i ( Alternate interior angles are equal)

Similarly, ∠D = ∠r ( Alternate interior angles)

But, ∠i = ∠r

⇒ ∠A = ∠D

Also, the tourist and the tower is perpendicular to the ground surface.

⇒ m∠B = m∠E = 90°

Now, in ΔABC and ΔDEC

∠A = ∠D (Proved above)

m∠B = m∠E = 90°

So, by AA postulate of similarity of triangles, ΔABC ~ ΔDEC

As the sides of similar triangles are proportional to each other

$\frac{AB}{DE}=\frac{BC}{EC}\\\\\implies\frac{1.92}{x}=\frac{0.4}{87.6}\\\\\implies x=\frac{87.6\times 1.92}{0.4}\\\\\bf\implies x = 420.48\textbf{ meters}$

Hence, The height of the tower = 420.48 meters

5 0

3 years ago

) An instructor gives his class a set of 18 problems with the information that the next quiz will consist of a random selection

RSB [31]

Answer:

The probability the he or she will answer correctly is 1.5%

Step-by-step explanation:

In all, there are 18 problems. In this question, the order of which the problems are sorted for the quiz makes no difference. For example, if the question A of the quiz is P1 and question B P2, and question A P2 and question B P1, it is the same thing.

There are 18 problems and 9 are going to be selected. So, there is going to be a combination of 9 elements from a set of 18 elements.

A combination of n elements from a set of m objects has the following formula:

$C_{(m,n)} = \frac{m!}{n!(m-n)!}$

In this question, m = 18, n = 9. So the total number of possibilities is:

$T_{p} = C_{(18,9)} = \frac{18!}{9!(18-9)!} = 48620$

Now we have to calculate the number of desired outcomes. This number is a combination of 9 elements from a set of 13 elements(13 is the number of problems that the student has figured out how to do).

Now, m = 13, n = 9. The number of desired possibilities is:

$D_{p} = C_{(13,9)} = \frac{13!}{9!(13-9)!} = 715$

The probability is the number of desired possibilities divided by the number of total possibilities. So

$P = \frac{715}{48620} = 0.015 = 1.5%$

The probability the he or she will answer correctly is 1.5%

3 0

3 years ago

How are determinants used to find areas of polygons?

ANTONII [103]

When you arrange the N points in sequence around the polygon (clockwise or counterclockwise), the area is half the magnitude of the sum of the determinants of the points taken pairwise. The N determinants will also include the one involving the last point and the first one.

For example, consider the vertices of a triangle: (1,1), (2,3), (3,-1). Its area can be computed as
(1/2)*|(1*3-1*2) +(2*-1-3*3) +(3*1-(-1)*1)|
= (1/2)*|1 -11 +4| = 3

4 0

3 years ago

Which expression can be used to find the surface area of the following triangular prism? *picture of a triangular prism* Choose

KIM [24]

Answer:

A. 24+24+120+160+200

Step-by-step explanation:

Surface area of the triangular prism= addition of the area of each shape that forms the prism

There are two triangles

Area of a triangle=1/2*base*height

=1/2*8*6

=1/2*48

=24

Area of two triangles=24+24

There are 3 rectangles with different dimensions

Back rectangle=length×width

=20×6

=120

Bottom rectangle=length ×width

=20x8

=160

Top rectangle=length × width

=20×10

=200

Surface area =Area of two triangles + Back rectangle + Bottom rectangle + Top rectangle

=24+24+120+160+200

5 0

3 years ago

Read 2 more answers

Ma Find the co-ordinate the image of a point 6,4). Rotate it than 270 de acee

telo118 [61]

Answer:

(4, - 6 )

Step-by-step explanation:

Under a counterclockwise rotation about the origin of 270°

a point (x, y ) → (y, - x ) , thus

(6, 4 ) → (4, - 6 )

6 0

3 years ago