math Flashcards
what are the steps to compass bearings
Step 1- workout whether angles are in north or south
Step 2- workouts whether we angles are east or Wests
Step 3- what is the angle of the swing
steps for true bearings
Step 1- start from north and measure swing to the direction
Step 2 quote the angle and add T make sure it’s 3 numbers
what way does bearings and trig go
Bearings is clockwise
Trig is anticlockwise
first quadrant rule
Only first quadrant adds up to 90° Sin30=cos60°. It’s all positive
second quadrant rue
From 90° to 180° Sin is only positive rest is negative Sin180° (180-140)= Sin 40°
third quadrant rule
From 180-270° only tan is positive
Sin190° (180+10) = -sin10°
fourth quadrant rule
Adds up from 270-360° cos is only positive Cos330°= (360-330) cos30°
give me the angles for your hand
Thumb- 0
Pointer- 30°
Middle- 45°
Index- 60°
Pinky- 90°
sin ratio
Sin = [number of fingers below]/ 2
cos ratio
Cos- [ number of fingers above] / 2
tan ratio
Tan- [ number of fingers below]/ [number of fingers above]
cos
Adjacent/ hypotenuse
sin
Opposite/ hypotenuse
tan
Opposite/ adjacent
method to solve right angles
- Pythagorean’s theorem
- Soh cah toa
method to solve non right angles
- Law of sines SinA/a = SinB/b= SinC/c
- Law of cosines
Find missing side- a^2= b^2+c^2 -2bc CosA
Find missing angle- b^2+c^2- a^2/2bc
what is the sign rule
Used to find non right angles (Butterfly) label capital and lowercase ABC and abc find the butterfly and use the rule SinA/a = SinB/b= SinC/c
what is the method to solve third sign using cosine
Can find a missing side
Find missing side- a^2= b^2+c^2 -2bc CosA
what is the method to find an angle using cosine
Can find a missing angle
Find missing angle- b^2+c^2- a^2/2bc
if you already have an angle how do you find area
1/2bc SIN A
1/2bc SIN B
1/2bc SIN C
When should the SINE rule be used in non right angled triangles?
When there’s a cross between two angles and two sides, where only one side or angle is unknown (looks like the wings of a butterfly)
