They ask me that all the time ;)
Answer:
Step-by-step explanation:
Suppose you draw line AC and calculate the midpoint of AC.
To verify the correctness of your midpoint, you'd find the distance from A to the midpoint, M, as well as the distance from the midpoint, M, to C. If these two distances are equal, then you've found that your midpoint calculation was correct.
Answer:

Step-by-step explanation:
We require to find the third side of the triangle.
Using Pythagoras' identity
The square on the hypotenuse is equal to the sum of the squares on the other 2 sides.
let x represent the third side, then
x² + 7² = 8², that is
x² + 49 = 64 ( subtract 49 from both sides )
x² = 15 ( take the square root of both sides )
x = 
Thus
sinΘ =
= 
Answer:
3 • (2x - 7) - (x + 4) = 0
then do 3.1 Pull out like factors :
5x - 25 = 5 • (x - 5)
5 • (x - 5) = 0
4.2 Solve : x-5 = 0
Add 5 to both sides of the equation :
x = 5
Step-by-step explanation: