Quadrilaterals Trapezoids Parallelograms Rectangles Squares and Rhombuses

in this video we're going to talk about quadrilaterals quadrilateral is simply four-sided figure and it turns out that the interior angles of four-sided figure adds up to 360 so in this example angle plus angle plus angle plus angle adds up to 360° now there are certain types of quadrilaterals that have specific names this particular quadrilateral is the trapezoid in this figure these two lines are parallel now if you have an isos trapezoid these two sides are congruent so make sure you're aware of that in addition the angles opposite to those two sides are congruent if it's an isos trapezoid the next shape that you needs to be familiar with is the parallelogram which looks like this in the parallelogram these two lines are parallel and these two lines are also parallel in addition to being parallel the opposite sides are congruent so those sides are congruent and these two sides are congruent as well so that's the parallelogram keyw parallel opposite sides are parallel to each other the next figure that you need to know is the rectangle in rectangle all four angles are congruent they're all right angles 90° 90 * 4 is 360 opposite sides are congruent these two sides are equal to each other and the opposite sides are parallel as well so the rectangle is like parallelogram but the angles are 90 so these two sides are parallel to each other and the top and bottom line are parallel to each other so that's the rectangle the next shape that you need to be familiar with is the rhombus in the rhombus all four sides are congruent to each other this might not be drawn to scale but it's supposed to be like that let me draw better picture so all four sides are congruent and the diagonals BC each other at right angles so each of these angles are right angles the square is similar to rhombus and rectangle but also different from each like rectangle all four angles of square are 90° and like rhombus all four sides are congruent so in square everything is basically equal to each other and like parallelogram opposite sides are parallel to each other so each of these shapes are known as quadrilaterals now let's work on some math problems so let's say if we have this four-sided quadrilateral let's say this is and this angle is 58° and this one is 73 and this angle is 117° go ahead and find the value of now if you recall the sum of all the interior angles of quadrilateral or four-sided figure adds up to 360 so that means 58 + 73 + 117 + all four angles have to add up to 360 if we add 58 and 73 that's 131 next if we add 131 + 117 that's 248 so 248 + is equal to 360 to find the value of we need to subtract both sides by 248 so 360 minus 248 that's about 112 so that's how you could find the missing angle in quadrilateral as long as you keep in mind that all four angles have to add up to 2 360 it's going to be piece of cake to solve these types of problems now let's work on another example let's call this angle and so angle is equal to 5x + 10 angle is 10 - 30 angle is 95° and angle is 4X go ahead and find the measure of angle feel free to pause the video and work on this example so we know that all four angles + + plus has to add up to 360 angle is 5x + 10 angle is 10 - 30 angle angle is 95 angle is 4X all of that has to add up to 360 so what we need to do is combine like terms 5x + 10 is 15x 15x + 4x that's 19x -30 + 95 or 95 - 30 that's 65 65 + 10 is 75 so 19x + 7 5 is equal to 360 now let's subtract both sides by 75 360 - 75 is 285 and 285 ID 19 will give us an value of 15 so now that we have the value of we could find any angle that we want to find so let's go ahead and find angle so angle is 5x + 10 and let's replace with 15 so it's 5 * 15 + 10 5 * 15 is 75 75 + 10 is 85 so that's the final answer it's 85° that's the measure of angle now want to show you one of my algebra courses that might be useful to you if if you ever need it so go to udemy.com now in the search box just type in algebra and it should come up so it's the one with the image with the black background so if you select that option and if you decide to go to course content you can see what's in this particular course so the first section basic arithmetic for those of you who want to focus on addition subtraction multiplication and division and it has video quiz at the end it's multiple choice video quiz you can pause it work on the problems and see the solutions it covers long division multiplying two large numbers and things like that the next tutorial is on fractions adding subtracting fractions multiplying dividing fractions converting fractions into decimals and so forth so you can also take look at that next solve the linear equations which we covered and just more examples if you need more help with that the next topic order of operations which is also useful graph in linear equations you need to know how to calculate the slope needs to be familiar with the slope slope intercept form standard form and just how to tell if lines are parallel perpendicular and so forth and is quiz that goes with that as well the next topic is on inequalities and absolute value Expressions which are also seen typical algebra course and then we have polinomial and that's long section and then factoring you just that's another topic you need to master and then system of equations you can solve it by elimination substitution there's also word problems as well sometimes you got to solve equations with three variables and so that could be helpful next quadratic equations how to use quadratic formula how to graph them how to convert between standard and vertex form and then you have rational expressions and radical expressions solving radical equations simplifying it things like that and every section has quiz so you can always review what you've learned if you have test the next day so here we have complex imagine numbers you need to know how to simplify those exponential functions logs have lot of videos on logs and then this is just functions in general vertical line tests horizontal line tests how to tell what functions even or odd and then conic sections graph in circles hyperbolas ellipses parabas and things like that there's two video quizzes because it's actually long section and finally arithmetic and geometric sequences and Series so that's my algebra course if you want to take look at it and let me know what you think