Let triangle ABC square at A(AB < AC) . Let D and E be the midpoints of the lines BC and AC respectively. Draw DF perp AB at F. Let O be the intersection of AD and FE. a. What is the quadrilateral AFDE? Prove. b. Let I be the point symmetrical to D about AC. Prove that DI is the bisector of angle ADC. C. Draw AH as altitude of triangle ABC Prove angle FHE is right angle

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

32

step-by-step explanation:

these are your clues: 1. kim ran 18 races2. this was four fewer races than twice thenumber, notice it says twice the number, so you would do the equation 18x2-4; which equals the number 32.thus, 32 is your answer.