1. Geometry of Triangles

3. Trigonometry (from the Greek trigon triangle and metron measure) is a branch of mathematics that uses the relationships between the sides and angles of triangles. The earliest applications of trigonometry were in the fields of navigation, surveying and astronomy. By using trigonometry, it became possible to calculate distances that could not be measured directly, such as the distance between the Earth and the Moon, or the height of a very tall structure. The use of trigonometry was first mentioned on an Egyptian papyrus in about 1800 BC.It is clear that people in ancient civilisations were able to measure angles accurately. The pyramids of Egypt and the megaliths of Stonehenge in England were built using a detailed knowledge of angles. Applications of trigonometry are found in physics and virtually all branches of engineering,particularly in the study of periodic phenomena, such as sound vibrations and the flow of alternating current and now we have a true story

12. note to self START HERE TUES