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3 years ago

Find a · b. |a| = 60, |b| = 30, the angle between a and b is 3π/4.

1 answer:

8 0

The dot product is used to determine the magnitude of the resultant vector of two component vectors. It is expressed as a·b. It does not literally mean that you multiply their values. Instead, you multiply their matrices. However, since we cannot find matrices, let's just find the resultant vector through theorems involving triangles. By cosine law:

R = √[a² + b² - 2abcos(3π/4)]
R = √[60² + 30² - 2*60*30*cos(3π/4)]
R = 83.94

Thus, a·b = 83.94

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Apply the commutative property to 13 × 7 × 21 to rearrange the terms and still get the same solution.

Andru [333]

Hey there!!
The answer is (13)(21)(7).

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7 0

3 years ago

Solve in simultaneou linear equation.

dangina [55]

Answer:

The bag costs 1500, while the umbrella cost 500

Step-by-step explanation:

Let the cost of the bag be b and the cost of the umbrella be u

Total cost is;

b + u = 2,000 •••••(i)

From the second part of the question;

b = 5u-1000 ••••••(ii)

Substitute ii into i

5u-1000 + u = 2000

6u = 2000 + 1000

6u = 3000

u = 3000/6

u = 500

To get b, substitute the value of u into equation ii

b = 5(500)-1000

b = 2500-1000

b = 1500

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2 years ago

I need the answer to number 4

zloy xaker [14]

Answer: 6.3

Step-by-step explanation

I did this today and it's easy but you have to show a lot of work well I did but you don't have to you can just circle it in

5 0

3 years ago

Given the length of three sides of a triangle, which is a right triangle?

RSB [31]

The aides of a right triangle will always satisfy the Pythagorean relationship ...

 a² + b²= c²

We can take each of these and try it out:

(1) ... 10² + 24² = 100 + 576 = 676
 √676 = 26 Yes.

(2) ... 12² + 18² = 144 + 324 = 468
 √468 = 21.6, not 20. No.

(3) ... 15² + 26² = 225 + 676 = 901
 √901 = 30.017 Awfully close. As an engineer, I'll buy this one. Yes.

(4) ... 40² + 50² = 1,600 + 2,500 = 4,100
 √4,100 = 64.03, not 80. No.

8 0

2 years ago

Read 2 more answers

Find the roots of:

Elena-2011 [213]

$\large\displaystyle\text{$\begin{gathered}\sf \pmb{1) \ 2x^3-7x^2+8x-3=0 } \end{gathered}$}$

Synthetic division is used since the equation is of the third degree. The divisors of -3 are 1, -1, 3, +3. So:

| 2 -7 8 -3

1 | 2 -5 3

| 2 -5 3 0

1 | 2 -3

2 -3 0

So the factorization is (x-1)² (2x-3)=0. So:

$\bf{ x_1=x_2=1 \qquad x_2=\dfrac{3}{2} }$

$\large\displaystyle\text{$\begin{gathered}\sf \pmb{2) \ x^3-x^2-4=0 } \end{gathered}$}$

Synthetic division is used since the equation is of the third degree. The divisors of -4 are 1, -1, 2, -2, 4, -4. So:

| 1 -1 0 -4

2 | 2 2

1 2 2 0

So the factorization is (x-2)(x²+x+2)=0 . When calculating the discriminant of the trinomial, it is concluded that it has no roots since the result is negative. So you only have one solution.

$\bf{ 1^2-4(2)(2)=1-16=-15 < 0 \quad \Longrightarrow \quad x=2 }$

$\large\displaystyle\text{$\begin{gathered}\sf \pmb{3) \ 6x^3+7x^2-9x+2=0 } \end{gathered}$}$

Synthetic division is used since the equation is of the third degree. The divisors of 2 are 1, -1, 2, -2. So:

| 6 7 9 2

-2 | -12 10 -2

6 -5 1 0

So the factorization is (x+2)(6x²-5x+1)=0 . The quadratic equation is solved by the general formula:

$\bf{ x_{2, 3}&=\dfrac{5\pm \sqrt{(5)^2-4(6)(1)}}{2(6)}=\dfrac{5\pm \sqrt{25-24}}{12}=\dfrac{5\pm 1}{12} }}$

$\large\displaystyle\text{$\begin{gathered}\sf \begin{matrix} x_1=-2&\ \ \ \ \ \ x_{2}=\dfrac{6}{12} \qquad &\ \ \ x_3=\dfrac{4}{12}\\ &\ \ \ x_2=\dfrac{1}{2} \qquad &x_3=\dfrac{1}{3} \end{matrix} \end{gathered}$}$

6 0

2 years ago