# GeoGebra 4.2 Sneak Peek 4: Defaults and Advanced Sections

This is the fourth part of the GeoGebra 4.2 Sneak Peek Series.  In the second and third part of this series, we have discussed about the Object Properties as well as Graphics and Layout sections. These sections are tabs located in the GeoGebra Preferences window. In this post, we discuss the remaining two  more sections of the Preferences window, the Defaults and Advanced sections.

The Preferences window can be displayed by right clicking an object and then clicking Object Properties in the context menu. It can also be displayed using the  the View menu and the choosing Advanced or using the Preferences icon located at the upper-right part of the Graphics view. Continue reading

# Calculating the Area Under a Curve: An Intuitive Introduction

##### Introduction

One of the most fundamental problems that gave birth to integral calculus was the calculation of areas bounded by curves. The Greeks used method of exhaustion to remedy this problem, particularly on finding the area of a circle. After Descartes’ and Fermat’s invention of Coordinate Geometry, algebraic solutions were utilized.

One of the strategies used to find the area under the function $f$ between $a$ and $b$ is to divide it into sub-intervals and form rectangles as shown in the first figure. Clearly, as the number of rectangles increases, the sum of all the areas of the rectangles gets closer and closer to the area of under the curve. Continue reading

# How to Right Click in the GeoGebra Chrome App

If you have used the GeoGebra Chrome App, you have surely noticed that there is no right click function. How do we solve this problem? GeoGebra expert Linda Fahlberg-Stojanovska gives us tips on how to remedy this problem in the tutorial below.

The Chrome App enables users to use GeoGebra on tablets and devices that do not support Java. Currently, GeoGebra developers are also developing real tablet apps particularly for the iPad and Android tablets.

# Math Word Problems: Solving Age Problems Part 3

This is the third part of the Solving Age Problems of the Math Word Problem Solving Series. In this post, we discuss more complicated age word problems.

Problem 7

Anna who is $6$ years old and his father Ben who is $27$ years old have the same birthday. In how many years will Ben be twice as old as Anna?

Solution

As years go by, the number of years added to Ben’s and Anna’s ages is the same. If we let the number of years that have gone by be $x$, then in $x$ years, their ages will be

Ben’s Age: $27 + x$

Anna’s Age: $6 + x$

Since in $x$ years, Ben will be as twice as old as Anna, if we multiply Anna’s age by $2$, their ages will be equal. So, we can now set up the equation Continue reading

# 1500+ Mathematics Video Lectures

In addition to the 5000 videos that I have shared to you last year, I have recently discovered more than 1500 links to mathematics video lectures in Pinterest. The links cover a wide variety of topics which include K-12 Mathematics, Math Interviews and Humor, Famous Mathematicians,  Student Lectures, and many more.

The collection also includes undergraduate and graduate content topics such as Abstract Algebra, Graph Theory, Topology, Number Theory, Optimization, etc.