Answer with Step-by-step explanation:
We have to prove that
by using Euler's formula
Euler's formula :

By using Euler's identity, we get





Comparing imaginary part on both sides
Then, we get

Hence, proved.
Note necessary facts about isosceles triangle ABC:
- The median CD drawn to the base AB is also an altitude to tha base in isosceles triangle (CD⊥AB). This gives you that triangles ACD and BCD are congruent right triangles with hypotenuses AC and BC, respectively.
- The legs AB and BC of isosceles triangle ABC are congruent, AC=BC.
- Angles at the base AB are congruent, m∠A=m∠B=30°.
1. Consider right triangle ACD. The adjacent angle to the leg AD is 30°, so the hypotenuse AC is twice the opposite leg CD to the angle A.
AC=2CD.
2. Consider right triangle BCD. The adjacent angle to the leg BD is 30°, so the hypotenuse BC is twice the opposite leg CD to the angle B.
BC=2CD.
3. Find the perimeters of triangles ACD, BCD and ABC:



4. If sum of the perimeters of △ACD and △BCD is 20 cm more than the perimeter of △ABC, then

5. Since AC=BC=2CD, then the legs AC and BC of isosceles triangles have length 20 cm.
Answer: 20 cm.
For this case, the first thing we are going to do is write the generic equation of motion for the vertical axis.
We have then:

Where,
- <em>g: acceleration of gravity
</em>
- <em>vo: initial speed
</em>
- <em>h0: initial height
</em>
For the first body:

For the second body:

By the time both bodies have the same height we have:


Rewriting we have:



Clearing time:

Answer:
it takes 18.31s for the two window washers to reach the same height