**Odd numbers**
-Trigonometry is the study of triangles using functions like sine, cosine, tangent, cosecant, secant and cotangent

-It was theorised officialy by Hipparchus, a greek mathematician, but it has first been used during the egyptian and babylonian period.

-Used in physical engineering, architecture, navigation, astronomy (To calculate distances and height)

-Also used in urban planning which is evident in rome, with the presence of aqueducts and many grand buildings such as the pantheon, colosseum etc.

-Trigonometry is actually ratios that has been converted into angles

**Q: **Why do we need to come up with sin, cos and tan when we already know the sum of angles in a triangle and we already have Pythagoras theorem.

**A:** It is used in metrology, to minimise error

Important notes:

-All museums in England is free

-Some free walking tours are conducted by experts (win-win situation)