Answer:
trigonometry (guessing)
Explanation:
ellipse: is the shape of an orbit : looks like an oval
periapsis : shortest distance between something like the moon and the planet its orbiting around like the earth
parallax is triangulation. like how gps works. looking at a star one day and then looking at it again 6 months later, an astronomer can see a difference in the viewing angle for the star. With trigonometry, the different angles yield a distance. This technique works for stars within about 400 light years of earth
https://science.howstuffworks.com/question224.htm
By comparing the intrinsic brightness to the star's apparent brightness we can calculate the distance of stars
1/r^2 rule states that the apparent brightness of a light source is proportional to the square of its distance.Jan 11, 2022
https://www.space.com/30417-parallax.html
alternative distance measurement for stars used by most astronomers is the parsec. A star with a parallax angle of 1 arcsecond has a distance of 1 parsec, or 1 parsec per arcsecond of parallax, which is about 3.26 light years
blossoms.mit.edu 
.
 
        
             
        
        
        
Answer:
 x = 6.94 m
Explanation:
For this exercise we can find the speed at the bottom of the ramp using energy conservation
Starting point. Higher
             Em₀ = K + U = ½ m v₀² + m g h
Final point. Lower
              = K = ½ m v²
 = K = ½ m v²
             Em₀ = Em_{f}
             ½ m v₀² + m g h = ½ m v²
             v² = v₀² + 2 g h
              
Let's calculate
              v = √(1.23² + 2 9.8 1.69)
              v = 5.89 m / s
In the horizontal part we can use the relationship between work and the variation of kinetic energy
             W = ΔK
             -fr x = 0- ½ m v²  
                
Newton's second law
               N- W = 0
      
The equation for the friction is
                fr = μ N
                fr = μ m g
We replace
              μ m g x = ½ m v²
              x = v² / 2μ g
Let's calculate
             x = 5.89² / (2 0.255 9.8)
             x = 6.94 m
 
        
                    
             
        
        
        
careful observation, curiosity, logic, creativity, skepticism, and objectivity