Arock is dropped into a water well and it travels approximately 16t2 in t seconds. if the splash is heard 3.5 seconds later and the speed of sound is 1087 feet/second, what is the height of the well?

T1 + T2 = 3.5 : T1 time for the rock to reach bottom of well and T2 time for the sound to reach the top of the well. 16 * T12 = 1087 * T2 : same distance which the height of the well. T2 = 3.5 - T1 : solve for T2 16 * T12 = 1087 * (3.5 - T1) T1 = 3.34 seconds Height = 16 * (3.34)2 = 178 feet (to the nearest unit)   

Okay so for every triangle has three angles that always add up to 180 degrees. and to tell the difference between whether they are secure, right or obtuse is that acute: has one angle that is less than 90 degrees. right triangle means there is at least one angle that is exactly 90 degrees. and an obtuse angle has an angle that is bigger than 180 degrees. i’ll do #13 as an example: 13. 40 and 50 so if every triangle has 180 degrees 40+50= 90 degrees then180-90= 90 degrees so the third angle is 90 degrees and because this triangle has a 90 degree angle it means it is a right triangle