# Category: Math 11

## Pre Calc – Week 17

One thing I learned this week in Pre Calc 11 is **how to find the side of a triangle using Cosine Law. **The Cosine Law is used when you need to find a third side of a triangle. **Tip:** When trying to find a third angle of a triangle use the **Alternate Cosine Law**.

A trick to knowing when you are going to be using the Cosine Law is when you see a question asking to find the measurement of the third side of the triangle, and they give you the other two sides of the triangle and the angle between them.

Below is an example of a triangle where you need to find the third side. I will show how I determine what formula to use and how to solve…

## Pre Calc – Week 14

One thing I learned this week in Pre Calc 11 is **how to determine non-permissible values for rational expressions. **A **rational expression** is an algebraic expression that can be written as the quotient of two polynomials. A rational expression cannot contain roots of variables, or variables as exponents. Here are some examples of rational expressions, and expressions that are not rational expressions…

Rational expressions cannot have a denominator of 0. Therefore the variable in the denominator can not make the denominator equal to 0. The values for the variable that make the variable equal to zero are called **non-permissible values. **Follow the steps below I took to find the non-permissible value…

## Pre Calc – Week 15

## Pre Calc – Week 13

One thing I learned this week in Pre Calc 11 is **how to write absolute value functions in piecewise notation. **We already have learned about absolute values (reference back to week 3 blog post for reminder). This week we learned about piecewise notation, and how to understand and write it for a absolute value function.

Piecewise notation is used to describe a function that has different definitions for different parts of the graph. When writing absolute values we use piecewise notation to describe the absolute value of the number.

In the example below follow the steps I take to write a absolute value function in piecewise notation…

## Pre Calc – Week 12

One thing I learned this week in Pre Calc 11 is **how to solve systems of equations using substitution.** A way to solve a linear system is to use the substitution method. You use the substitution method by substituting one y-value in a equation with the other. While using the substitution method you first substitute y in the second equation with thefirst equation since y = y. After substituting y into the equation and solving for x the value of x can then be used to find y by substituting the number you found, with x. While using the substitution method you can also start by substituting x in the second equation with the first equation.

Below is a example of how I solved a systems of equations using the steps above…

## Pre Calc – Week 11

One thing I learned this week in Pre Calc 11 is **how to graph linear equations in two variables. **A linear equation divides a graph into two sections. A linear equation has variables to the first degree only, and the variables are never squared, cubed, or taken to any other power. A linear inequality looks very similar to a linear equation, the difference between the two is that a linear equation has a “equals” symbol and a linear inequality has a “inequality” symbol. When writing or understanding a graph of a linear inequality we shade one side of two sections divided by the linear equation. The side of the linear equation that is shaded is the region that will “satisfy” the inequality.

To find the region that will satisfy the inequality we choose a point (called the test point) on either side of the slope and plug it into the linear inequality. Then solve the linear inequality. If the inequality sign is true to the numbers then shade in the region, if not shade in the opposite region on the graph.

Below is a example of how I graphed a linear equation in two variables using the steps above…

## Pre Calc – Week 10

This week while studying for the midterm I had to look back at couple things from **Unit one Arithmetic and Geometric Series and Sequences. **To help practice studying for this unit in the mid term, I went through all my notes and picked out the most important things I need to know. I wrote them down on one piece of paper to use while going through and doing questions from this unit.

## Pre Calc – week 9

One thing I learned this week in Pre Calc 11 is **how to find the vertex of a quadratic equation that is in factored form.** The first step is to find the x-intercepts or “zeros” of the equation. Once you’ve determined the zeros/ x-intercepts, you find the average of the zeros by adding them and dividing them by two. Once you find that, you plug it in as X in the equation in order to find Y. The x and y coordinates are the coordinates to your vertex.

Below is a example of how I found the vertex of a quadratic equation in factored form using the steps above.