5
If tan θ = —— , calculate the value of cos θ:
4
Recall the definition of the tangent function:
sin θ
tan θ = ————
cos θ
5 sin θ
—— = ————
4 cos θ
Cross multiply:
5 · cos θ = 4 · sin θ
Square both sides:
(5 · cos θ)² = (4 · sin θ)²
5² · cos² θ = 4² · sin² θ
25 · cos² θ = 16 · sin² θ
But sin² θ = 1 – cos² θ. Substitute that for sin² θ into the equation above, then you get
25 · cos² θ = 16 · (1 – cos² θ)
25 · cos² θ = 16 – 16 · cos² θ
Isolate cos² θ:
25 · cos² θ + 16 · cos² θ = 16
(25 + 16) · cos² θ = 16
41 · cos² θ = 16
16
cos² θ = ———
41
4²
cos² θ = ————
(√41)²
Take square root of both sides:
4
cos θ = ± ———
√41
4 4
cos θ = – ——— or cos θ = ——— ✔
√41 √41
The sign of cos θ depends on which quadrant θ lies. Since you first have a positive value for tan θ, then that means θ lies either in the 1st or the 3rd quadrant.
• If θ is a 1st quadrant angle, then
cos θ > 0
4
cos θ = ——— ✔
√41
• If θ is a 3rd quadrant angle, then
cos θ < 0
4
cos θ = – ——— ✔
√41
I hope this helps. =)
Answer:
Famous Footwear has the most sheos.
Step-by-step explanation:
156/26=6=1%
6x100=600
At Fabco there are 600 sheos
130/13=10=1%
10x100=1000
At Famous Footwear there are 1000 sheos
Answer:
-8
Step-by-step explanation:
Hello!
What we do to one side of the equation we do to the other side
7 * p = -56
Divide both sides by 7
p = -8
The answer is -8
Hope this helps!
takes her 20 minutes to walk 1/2 a mile
2 miles=80 minutes
1/4= 10 minutes i think
so 80+10=1 1/2
{This is not my work!!!}
Hello from MrBillDoesMath!
Answer:
(3/4) a^(-5)b^(-3)c^2
Discussion:
(18 a^-3b^2c^6)/ (24 a^2b^5c^4) =
(18/24) a^ (-3-2) b^(2-5) c^(6-4) =
as a^-3/a^-2 = a ^ (-3-2) = a^(-5), for examples
(3/4) a^(-5)b^(-3)c^2
Thank you,
MrB
