Answer:
Empirical formula= COOH
Step-by-step explanation:
Molecular mass of the elements
Carbon= 12
Oxygen= 16
Hydrogen= 1
We divide the elements each with their molecular formula
Carbon= 2.4/12
Carbon= 0.2
Oxygen= 6.4/16
Oxygen= 0.4
Hydrogen= 0.2/1
Hydrogen= 0.2
Now we divide with the smallest result which is 0.2
Carbon= 0.2/0.2
Carbon = 1
Oxygen= 0.4/0.2
Oxygen= 2
Hydrogen= 0.2/0.2
Hydrogen= 1
So we have
Carbon 1, oxygen 2, hydrogen 1
Empirical formula= COOH
Cos(A-B) = cosAcosB + sinAsinB
<span>
cos(</span>π/2 - θ) = cos(π/2)cosθ + sin(π/2)sinθ
π/2 = 90°
cos(π/2) = cos90° = 0. sin(π/2) = sin90° = 1
cos(π/2 - θ) = cos(π/2)cosθ + sin(π/2)sin<span>θ
</span>
= 0*cosθ + 1*sin<span>θ = </span>sin<span>θ
Therefore </span>cos(π/2 - θ) = sin<span>θ
QED </span>
Answer:
B
Step-by-step explanation:
∠ABC= 180° -142° (adj. ∠s on a str. line)
∠ABC= 38°
∠BAC= 180° -133° (adj. ∠s on a str. line)
∠BAC= 47°
∠ACB= 180° -38° -47° (∠ sum of △)
∠ACB= 95°
n°= 180° -95° (adj. ∠s on a str. line)
n°= 85°
n= 85
