Trig Unit 3) Flashcards
when would you use the sin law
when you know 2 oppisites pair and an angle
make sure all same units on top/bottem
unit looking for is on top
how do you use the sin law
you set up so the same angle / length match up on neumerator and denominator
then cross multiply and divide
(if looking for angle rememeber to use -1 sin 2nd ans )
(cant have more then 1 varible in a equation )
when to use the cos law
when given 2 lengths with an angle in between
when know all lengths
when 2 angles are known and know one side length on triangle and one on the other what can you do to solve the angle between both triangles
go 180- whatever angle is then you can solve for other angle and then solve for whatever you need to
how do you proof the sin law
1- you draw a line down the center of the triangle to form a right angle so sinA =h/b and sin B=h/a
2- write out fromulas of sin in this senerio and solve both so h is isolated
3- now transitive property ( both = same thing) so combine formulas together by = sign
4- rearrange both sides by dividing
when directional questions how do you find angle in triangle
you subtract 90- (baring varible)
cos and sin laws both need how many varibles to solve
at least 3
what cos formula do you use for length
a2=b2c2–2bccosA
how do you figure out what angle is a when cos law finding angles
whatever angle you are looking for represents A so the oppisite side of that would be -a
when trying to solve for side and angle isnt given how do you solve
you would solve for the other angle that has a side length and use other oppisite angle - side pair to solve then you can sub 180-( angles
when using cos law to solve for angle what does the -a represent
whatever vale is -a is the angle youre solving for
