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3 years ago

Geometry

Mathematics

1 answer:

Mademuasel [1]3 years ago

6 0

DB is a median (given). It goes from vertex point D to midpoint B.

The point B is the midpoint of segment AC. So B cuts AC into two equal halves: AB and AC
Meaning AB = AC

AC = AB+BC ... segment addition postulate
AC = AB+AB ... substitution; replace BC with AB (valid because AB = AC)
AC = 2*AB
2*AB = AC
2*AB = 50 ... substitution; replace AC with 50
2*AB/2 = 50/2 ... divide both sides by 2
AB = 25 which is the answer

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Solve for x: 4 over 5 x + 4 over 3 = 2x x =

Naily [24]

Answer:

over 5 x + 4 over 3 = 2x

can't find x

Hi McDa:

Here's a couple hints. (I have no idea what you already understand. Please check out our posting guidelines.)

Express the Natural number 3 in Rational form 3/1.

Regarding the left-hand side above, have you learned the property that says we may multiply by the reciprocal of 3/1, instead of dividing by 3/1?

Step-by-step explanation: Incorrect? Let me know!

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3 years ago

ABCD is a trapezium with AB parallel to CD. Find the value of x and the value of y.

Natasha2012 [34]

Answer:

x = 107 , y = 60

Step-by-step explanation:

Each lower base angle is supplementary to the upper base angle on the same side, then

x + 73 = 180 ( subtract 73 from both sides )

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and

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3 0

3 years ago

A random variable X follows the uniform distribution with a lower limit of 670 and an upper limit of 750.a. Calculate the mean a

DENIUS [597]

You can compute both the mean and second moment directly using the density function; in this case, it's

$f_X(x)=\begin{cases}\frac1{750-670}=\frac1{80}&\text{for }670\le x\le750\\0&\text{otherwise}\end{cases}$

Then the mean (first moment) is

$E[X]=\displaystyle\int_{-\infty}^\infty x\,f_X(x)\,\mathrm dx=\frac1{80}\int_{670}^{750}x\,\mathrm dx=710$

and the second moment is

$E[X^2]=\displaystyle\int_{-\infty}^\infty x^2\,f_X(x)\,\mathrm dx=\frac1{80}\int_{670}^{750}x^2\,\mathrm dx=\frac{1,513,900}3$

The second moment is useful in finding the variance, which is given by

$V[X]=E[(X-E[X])^2]=E[X^2]-E[X]^2=\dfrac{1,513,900}3-710^2=\dfrac{1600}3$

You get the standard deviation by taking the square root of the variance, and so

$\sqrt{V[X]}=\sqrt{\dfrac{1600}3}\approx23.09$

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3 years ago

HELP

fgiga [73]

Answer:

Step-by-step explanation:

5 0

3 years ago

Find the value of the expression: −0.5(7b−12a)−(8.4a−14b) if a=−10; b=−6.

ELEN [110]

Replace a and b in the equation with their values given:

-0.5(7(-6)-12(-10)-(8.4(-10)-14(-6))

Multiply within the parentheses

-0.5(-42 + 120) -(-84 + 84)

Add inside the parenthesis:

-0.5(78)-0

Multiply:

-.05 x 78 = -39

The answer is -39

3 0

4 years ago