This week I learned how to use trigonometry to find angles and the length of sides.

Every trig equation is: ratio(reference angel)=side 1/side 2

Ratio (cos, sin, tan)

To find the length of sides using trig:

• First you have to look for clues, if there 2 on the outside (variable and the length of one side) and one on the inside (reference angle), then you know you have to use trig to find the missing length
• Next you have to label all the sides (hypotenuse, opposite and adjacent)
• Now you check what sides the clues are connected to (hypotenuse, opposite or adjacent)
• And finally you plug in the numbers into the equation and put it into your calculator

If the variable of the side ends up on the bottom of a fraction:

• Reciprocal both sides
• Multiply both sides by the denominator
• Plug it into your calculator

To find the angle using trig:

• Theta is the greek letter that represents the angle you have to find
• You have to use the inverse of tan, sin, or cos multiplied by the length of the side you have

WHY: to get the variable by itself you have to divide both sides by the cosine, sine or tangent. Since you can’t really divide the length by just the ratio so you have to move it on top (which gives it a negative 1 charge, which is the inverse of the ratio).

Example: