Vertical angles<span> are the angles opposite each other when two lines cross, so
</span>∠AOB and ∠DOC are vertical.
Answer:
8 and 6
Step-by-step explanation:
If you use x for the first number, and y for the second, you get equations of 3x+5y=54 and x-2=y.
You can substitute the second equation into the first one to solve it. This gives 3x+5(x-2)=54.
The brackets can be expanded to 3x+5x-10=54. Collecting like terms makes it 8x-10=54.
Next, we add 10 to both sides. This gives 8x=64.
From there, we isolate the x by dividing both sides by 8, giving x=8.
To work out the second number, we can sub 8 for x in either equation (I'm using the second one as it's simpler).
This comes to y=8-2, therefore y=6.
**This content is simultaneous equations, which you may wish to revise. I'm always happy to help!
We turn -5,12 into polar coordinates. It's a Pythagorean Triple so
r = 13 Ф=arctan(-12/5) + 180° ( in the second quadrant )
so -5 = 13 cos Ф, 12 = 13 sin Ф
12 sin x - 5 cos x = 6.5
13 sinФ sin x + 13 cos Ф cos x = 6.5
13 cos(x - Ф) = 6.5
cos(x - Ф) = 1/2
cos(x - Ф) = cos 60°
x - Ф = ± 60° + 360° k integer k
x = Ф ± 60° + 360° k
x = 180° + arctan(-12/5) ± 60° + 360° k
That's the exact answer;
x ≈ 180° - 67.38° ± 60° + 360° k
x ≈ 122.62° ± 60° + 360° k
x ≈ { 62.62°, 182.62°} + 360° k, integer k
Trig ratios can only be used on right triangles with acute measures.
If given an angle and there are adjacent and opposite sides, then use tan(opposite/adjacent)
If given an angle and there is an adjacent side and a hypotenuse, then use cosine(adjacent/hypotenuse)
If given an angle and there is an opposite and adjacent side, then use sin(opposite/hypotenuse)
A common mnemonic device used to memorize the trig rules is SOH-CAH-TOA
