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Try reviewing these fundamentals first

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Get Started NowStart now and get better maths marks!

Get Started NowStart now and get better maths marks!

Get Started NowStart now and get better maths marks!

Get Started Now- Intro Lesson3:48
- Lesson: 1a5:20
- Lesson: 1b6:42
- Lesson: 2a9:59
- Lesson: 2b4:03
- Lesson: 38:04
- Lesson: 412:32

In this lesson, we will learn:

- How to solve two dimensional vector problems using the law of sines and the law of cosines

- Often, vector equations in physics problems result in vector triangles which can be solved using trigonometry
- At least three pieces of information are needed to solve a triangle, which can be three side lengths (SSS), two side lengths and one angle (SSA, SAS), or one side length and two angles (SAA, ASA).
- Knowing three angles (AAA) does not let you solve a triangle since you will not be able to solve for the side lengths. There is no way to know the size of the triangle without more information.
- You can always solve a triangle that you know four or more pieces of information about.
- Vector triangles that do not contain right angles can be solved either by
__breaking vectors into their components__or using the__law of sines__and the__law of cosines__, which are trigonometric laws that apply to all triangles

**Law of Sines**

$\frac{a}{sinA} = \frac{b}{sinB} = \frac{c}{sinC}$

a,b,c: length of sides a,b,c

A,B,C: angles opposite sides a, b, c

**Law of Cosines**

$c^2 = a^2 + b^2 - 2ab \,cosC$

- Introduction
Introduction to solving two dimensional vector problems

- Overview of trigonometry strategies for different types of vector problems
- Definition of the law of sines and the law of cosines

- 1.
**Use the law of sines to solve triangles**a)Find the length of side c

b)Find the angle &theta

- 2.
**Use the law of cosines to solve triangles**a)For the following triangle:

- Find the length of the unknown side.
- Find the angle θ

b)A paper airplane is thrown 11.0 m [W], then thrown 14.0 m, then 16.0 m. The final throw returns it to its original position. Find the angle of the 14.0 m throw.

- 3.
**Solve a vector word problem using the laws of sines and cosines**

To get to school, Pauline leaves her house and walks due east 1.40 km, then takes a shortcut by walking 0.650 km [35° S of E] through a park. Find her displacement from home to school.

- 4.
**Solve a difficult vector triangle using geometry**

Solve the equation $\vec{A} + \vec{B} = \vec{C}$.