I don’t understand how that person got the answer
Math

Find the arc length parameter along the given curve from the point where tequals=0 by evaluating the integral s(t)equals=integral from 0 to t startabsolutevalue bold v left parenthesis tau right parenthesis endabsolutevalue d tau∫0tv(τ) dτ. then find the length of the indicated portion of the curve r(t)equals=1010cosine tcost iplus+1010sine tsint jplus+88t k, where 0less than or equals≤tless than or equals≤startfraction pi over 3 endfraction π 3.

How many kilograms of a 5% salt solution and how many kilograms of a 15% salt solution must be mixed together to make 45kg of an 8% salt solution?

In which quadrant does the point lie? write the coordinates of the point. a. quadrant ii; (–2, –4) b. quadrant iii; (2, 4) c. quadrant iii; (–2, –4) d. quadrant iv; (–4, –2)