Step-by-step explanation:
what is the main condition the lengths of the sides of a right-angled triangle have to fulfill ?
Pythagoras !
c² = a² + b²
c is the Hypotenuse (the baseline opposite of the 90 degree angle), a and b are the so-called legs (the sides enclosing the 90 degree angle).
only if there is a combination of the sides, for which the Pythagoras equation is true, do we have a right-angled triangle. otherwise not.
we also know CA = 18 - 7 - 3 = 8 cm
so, let's try
8² = 7² + 3²
64 = 49 + 9 = 58 wrong
7² = 8² + 3²
49 = 64 + 9 = 73 wrong
3² = 8² + 7²
9 = 64 + 49 = 113 wrong
so, there is no combination, where the Pythagoras equation is true, so it is NOT a right-angled triangle.
