<span>Congruence between two triangles means six items, all three sides and all three angles, are congruent. Thus the statement ABC DEF has a very precise meaning. It succinctly summarizes the six statements (assume lines atop these segments): ABDE, BCEF, ACDF, AD, BE, and CF. It is very important to maintain the vertices in the proper order. Not doing so is a common mistake.</span>
Usually, Δ stands for a difference: if you have two quantities a₂ and a₁, their difference a₂-a₁ can be shortened as Δa.
This said, your formula is not set up correctly: the linear speed can be found with the formula:
v = ω·r
where r is the radius and <span>ω is the angular frequency, which is given by:
</span>ω = Δα / Δt
Substituting this into the one above, you find the correct formula:
<span>v = (Δα / Δt) · r
The problem gives you directly </span>Δα, which is 1/3 rad, because does not say at what angle the point started moving and at what angle it stopped.
Similarly, for the time you have Δt, which is 20 s.
Therefore, plugging in the numbers you get:
v = (Δα / Δt) <span>· r = (1/3 </span>÷ 20) × 10 = 1/6 = 0.167 cm/s
Answer:
20 minutes
Step-by-step explanation:
since it decreased by 20% you can do 10% of 25 minutes and that is 2.5 minutes then double that and you'll get 5 minutes then just do 25 minutes- 5 minutes
