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. =)
Here is an example on how you should do your multiplication. The website should give you your answer to any multiplication.
Hope this helps love!! <3
Answer:
x = 4, y = 9
Step-by-step explanation:
The angles in a square are right, that is 90°
The diagonals bisect the angles , then
6x + 21 = 45 ( subtract 21 from both sides )
6x = 24 ( divide both sides by 6 )
x = 4
------------------------------------------------
The sides of a square are congruent , then
10y - 29 = 5y + 16 ( subtract 5y from both sides )
5y - 29 = 16 ( add 29 to both sides )
5y = 45 ( divide both sides by 5 )
y = 9
I can’t see the question b
Answer:
K1310.4
Step-by-step explanation:
Basic pay per hour = K7.20
Overtime pay during the week per hour = 1 1/2 * K7. 20 = K10.8
Weekends = 2 * K7.20 = K14.4
Basic hours per week = 70 hours
In a fortnight :
Basic hours = 70 * 2 = 140 hours :
Hence, Overtime during the week = (160 - 140) = 20 hours
Weekend hours = (4 +2) = 6 hours
Total earning :
(140 * 7.20) + (20 * 10.8) + (6 * 14.4)
1008 + 216 + 86.4
= K1310.4
