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3 years ago

Given that D is the midpoint of AB and B is the midpoint of AC which statement must be true a) AD= 1/3AC

Mathematics

1 answer:

garik1379 [7]3 years ago

3 0

Answer:

AD = 1/4AC

Step-by-step explanation:

Given that,

D is the the midpoint of AB

Therefore

AB = AD + DB

Since, D is the midpoint of the AB, therefore AD = DB

AB = AD + AD

AB = 2AD (i)

Similarly, B is the midpoint of AC

Hence,

AC = AB + BC

AC = AB + AB (because B is the midpoint)

AC = 2AB (ii)

By putting the value of AB from equation i to equation ii, we get

AC = 2(2AD)

AC = 4AD

AC/4 = AD

AD = 1/4AC

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Given: △ABC, AB=5sqrt2 <br> m∠A=45°, m∠C=30°<br> Find: BC and AC

Marysya12 [62]

BC is 10 units and AC is $5+5\sqrt{3}$ units

Step-by-step explanation:

Let us revise the sine rule

In ΔABC:

$\frac{AB}{sin(C)}=\frac{BC}{sin(A)}=\frac{AC}{sin(B)}$
AB is opposite to ∠C
BC is opposite to ∠A
AC is opposite to ∠B

Let us use this rule to solve the problem

In ΔABC:

∵ m∠A = 45°

∵ m∠C = 30°

- The sum of measures of the interior angles of a triangle is 180°

∵ m∠A + m∠B + m∠C = 180

∴ 45 + m∠B + 30 = 180

- Add the like terms

∴ m∠B + 75 = 180

- Subtract 75 from both sides

∴ m∠B = 105°

∵ $\frac{AB}{sin(C)}=\frac{BC}{sin(A)}$

∵ AB = $5\sqrt{2}$

- Substitute AB and the 3 angles in the rule above

∴ $\frac{5\sqrt{2}}{sin(30)}=\frac{BC}{sin(45)}$

- By using cross multiplication

∴ (BC) × sin(30) = $5\sqrt{2}$ × sin(45)

∵ sin(30) = 0.5 and sin(45) = $\frac{1}{\sqrt{2}}$

∴ 0.5 (BC) = 5

- Divide both sides by 0.5

∴ BC = 10 units

∵ $\frac{AB}{sin(C)}=\frac{AC}{sin(B)}$

- Substitute AB and the 3 angles in the rule above

∴ $\frac{5\sqrt{2}}{sin(30)}=\frac{AC}{sin(105)}$

- By using cross multiplication

∴ (AC) × sin(30) = $5\sqrt{2}$ × sin(105)

∵ sin(105) = $\frac{\sqrt{6}+\sqrt{2}}{4}$

∴ 0.5 (AC) = $\frac{5+5\sqrt{3}}{2}$

- Divide both sides by 0.5

∴ AC = $5+5\sqrt{3}$ units

BC is 10 units and AC is $5+5\sqrt{3}$ units

Learn more:

You can learn more about the sine rule in brainly.com/question/12985572

#LearnwithBrainly

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3 years ago

Matrix A = [6 -12 4 8]. What is matrix X if 1/2x=A?

Step2247 [10]

Answer:

$X = \left[\begin{array}{cccc}12&-24&8&16\end{array}\right]$

Step-by-step explanation:

A matrix is given by

$A = \left[\begin{array}{cccc}6&-12&4&8\end{array}\right]$

Now, we have to find the matrix X if $\frac{1}{2} X = A$

⇒ X = 2A

Now, multiplication of a constant with a matrix means multiplication with that constant with all the terms of the matrix.

So, $X = \left[\begin{array}{cccc}6 \times 2&-12 \times 2&4 \times 2&8 \times 2\end{array}\right]$

⇒ $X = \left[\begin{array}{cccc}12&-24&8&16\end{array}\right]$ (Answer)

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Vitek1552 [10]

Answer:

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Step-by-step explanation:

PEMDAS suggests you start with parenthesis

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