Answer:
AB = 20 tan55°
Step-by-step explanation:
Using the tangent ratio in the right triangle
tan55° =
=
=
( multiply both sides by 20 )
20 tan55° = AB
Answer:
See below
Step-by-step explanation:
It has something to do with the<em> </em><u><em>Weierstrass substitution</em></u>, where we have

First, consider the double angle formula for tangent:

Therefore,

Once the double angle identity for sine is

we know
, but sure, we can derive this formula considering the double angle identity

Recall

Thus,
Similarly for cosine, consider the double angle identity
Thus,

Hence, we showed 
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![5\cos(x) =12\sin(x) +3, x \in [0, 2\pi ]](https://tex.z-dn.net/?f=5%5Ccos%28x%29%20%3D12%5Csin%28x%29%20%2B3%2C%20x%20%5Cin%20%5B0%2C%202%5Cpi%20%5D)
Solving





Just note that

and
is not defined for 
By Sine Rule,
x/sin30° = 8/sin90°
x/0.5 = 8/1
So x = 4.
X+y=5 would be the correct one
In a full rotation, 360°, a point on the edge of a gear would travel a distance equal to its circumference. The circumference of a circle is:
C=2πr, and since we are only traveling 150°, we need to set up an appropriate ratio for circumference to the distance the point travels:
d/C=150/360
d=5C/12 and since C=2πr
d=10πr/12
d=5πr/12, and since r=4in
d=5*4π/12 in
d=20π/12 in
d=5π/3 in
d≈5.24 in (to nearest hundredth of an inch)