Question

Triangle ABC has perimeter 18 cm.
AB = 7 cm
BC = 3 cm
By calculation, deduce whether triangle ABC is a right-angled triangle.


Please be quick,,it’s a test!!

Answer 1

AB= 7cm

BC=3cm

AC= x

Perimeter of triangle = AB + BC + AC

18 cm = 7cm + 3cm + X

18cm = 10cm + X

X = 18cm - 10cm

X = 8cm.

The pythagorean theorem states that in a right triangle a2 + b2 = c2, where c is the length of the hypotenuse (the longest side opposite to the right angle) and a and b are the lengths of the other two sides.

AC^2 = AB^2 + BC^2

8^2 =7^2 + 3^2

64 = 49 + 9

64 = 58

Since the equation is not true, we can deduce that ABC is NOT a right triangle.

Answer 2

So first let’s find the unknown side of the triangle. We are given AB=7cm and BC=3cm.
7+3=10
18-10=8cm
The unknown side (AC) is 8cm.
Use the Pythagorean Theorem to determine whether triangle is a right triangle. a^2+b^2=c^2
7^2+3^2=8^2
49+9=64
58=64
Triangle ABC is not a right angles triangle