Trigonometry

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In a right-angled triangle, the side opposite to 90° is the longest side and it is called hypotenuse.

Hypotenuse – c, other two sides a, b.

Pythagoras’ Theorem: a² + b² = c²

How to determine whether a triangle is right angled, when given 3 sides?

Square the largest side, c² .

Check whether this is equal to the sum of the squares of the other two sides.

That is check whether c² = a² + b² .

If equal, then the triangle is right angled.

Does three sticks of length 5 cm, 12 cm and 13 cm form the sides of a right angled triangle?

Since 13² = 5² + 12² , they form a right angled triangle.

In a right-angled triangle, the side opposite to 90° is called hypotenuse.

Opposite side is the side opposite to a considered angle.

Third side is called adjacent side.