Math help with triangles please help (15 points)

Prove that (a-b) x (a+b)=2a x b is true.<br> (a and b are vectors)

Anon25 [30]

(a-b) X (a+b)
= aXa - bXa +aXb -bXb (distributing)

Now, cross product of a vector with itself = 0
so, aXa = 0, bXb = 0

Also, aXb = - bXa

so,
(a-b) X (a+b) = 0 + aXb + aXb + 0
= 2aXb

hence, proved :)

6 0

3 years ago

Read 2 more answers

Jon buys a shirt for $40 and then buys socks for $15. He lives in Maine and their

gulaghasi [49]

Jon pays $40 and $15. This means that he pays a total of $55. You multiply the total cost by 0.05, which is $2.75. To convert a number to a percentage, multiply it by 100. So, 0.05 as a percent is equal to 5%.

His sales tax will be $2.75.

6 0

2 years ago

A triangle has side lengths of 10, 20, and 30. what type of triangle is it

Alexeev081 [22]

Right triangle bc a^2+b^2=c^2. (Pythagorean theorem)

4 0

3 years ago

Name all sets of numbers to which each real number belongs. 2/3

mel-nik [20]

2/3 belongs to rational numbers.

4 0

3 years ago

Please help ASAP! The terminal side of an angle θ in standard position passes through the point (2,-5). calculate the values of

Troyanec [42]

Answer:

$sin(x)=\frac{opp}{hyp}=\frac{5}{\sqrt{21}}=\frac{5\sqrt{21}}{21}\\cos(x)=\frac{adj}{hyp}=\frac{2}{\sqrt{21}}=\frac{2\sqrt{21}}{21}\\tan(x)=\frac{opp}{adj}=\frac{5}{2}\\csc(x)=\frac{hyp}{opp}=\frac{\sqrt{21}}{5}\\sec(x)=\frac{hyp}{adj}=\frac{\sqrt{21}}{2}\\cot(x)=\frac{adj}{opp}=\frac{2}{5}$

Step-by-step explanation:

Start by drawing out the triangle on the graph:

(See picture)

(By the drawing you can judge me that I am a really bad artist)

Theta and the side lengths are labeled, the hypotenuse has a length of √21 by Pythagora's theorem. Now, time to put everything to the trigonometric functions:

$sin(x)=\frac{opp}{hyp}=\frac{5}{\sqrt{21}}=\frac{5\sqrt{21}}{21}\\cos(x)=\frac{adj}{hyp}=\frac{2}{\sqrt{21}}=\frac{2\sqrt{21}}{21}\\tan(x)=\frac{opp}{adj}=\frac{5}{2}\\csc(x)=\frac{hyp}{opp}=\frac{\sqrt{21}}{5}\\sec(x)=\frac{hyp}{adj}=\frac{\sqrt{21}}{2}\\cot(x)=\frac{adj}{opp}=\frac{2}{5}$

(Suppose that x is theta as I can't type it)

By some basic understanding that's all that I can do.

3 0

2 years ago