Trigonometry theorem, Summaries of Mathematics

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TRIGONOMETRY

01 - PYTHAGORAS THEOREM

Pythagoras’ (Pythagorean) Theorem states that:

“In a right-angled triangle, the square of the hypotenuse is equal to the sum

of the squares of the other two sides.”

Here’s a Video 

We use Pythagoras Theorem to find missing sides in right-angled triangles.

Example 2:

Find the height of an isosceles triangle with base 8 cm and equal sides of

length 10 cm.

Solution:

𝟐

𝟐

𝟐

𝟐

𝟐

𝟐

𝟐

𝟐

10 cm 10 cm

8 cm

4 cm

a

∴ height = 9.2 cm

Example 3:

Find the length CD.

A

C

D B

3 cm 4 cm

12 cm

Solution:

𝟐

𝟐

𝟐

𝟐

𝟐

𝟐

𝟐

𝟐

𝑫𝑩 = 𝟓 cm

5cm

𝟐

𝟐

𝟐

𝟐

𝟐

𝟐

𝟐

𝟐

𝑪𝑫 = 𝟏𝟑 cm