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MJ2 Ch 10.5 - Quadrilaterals Bellwork Draw the triangles and find the value of x 1. 2. x° 34° 56° 53° x° Assignment Review Reminder: Your Triangle Poster is Due on _________ I will add 5 points to your grade if your poster is handed in on ___________ Unfortunately, If the poster is not handed in by ________ I will give you a zero (0) as I do not accept late assignments! Before we begin… Please take out your notebook and get ready to work… For the past couple of days we have been studying angles and triangles… Today we will look at quadrilaterals… Raise your hand if you know what a quadrilateral is… Quadrilaterals Correct…a quadrilateral is a closed figure with 4 sides and 4 angles… Raise your hand if you can name some examples… Objective Students will classify and find the missing angle measure of quadrilaterals. Classifying Quadrilaterals When classifying quadrilaterals you use the name that best describes it… That means we all need to have the same understanding of the characteristics of each type of quadrilateral Please copy the vocabulary on the next slide… Vocabulary Quadrilateral – any 4 sided, 4 angle figure Trapezoid – a quadrilateral with one pair of parallel sides Parallelogram – a quadrilateral with opposite sides parallel and opposite sides congruent Rectangle – a parallelogram with 4 right angles Square – a parallelogram with 4 right angles and 4 congruent sides Rhombus – a parallelogram with 4 congruent sides Comments When viewing pictures of quadrilaterals there are 2 types symbols that you need to be aware of The hash mark (/) means the sides are congruent. If multiple sides are congruent you will see 1 or 2 hash marks The arrow () indicates that the sides are parallel. If multiple sides are parallel you will see 1 or 2 arrows. Lets look at some examples… Examples Square: 4 right angles & 4 congruent sides Trapezoid – 1 set of parallel sides Missing Angle Measurements All the angles in any quadrilateral equal 360° . To find the missing measure use the same process as finding the angles of a triangle. 1. Add up the given angles and subtract from 360° . 2. Lets look at an example… Example Before you begin…look at angle x. Will it be >90°, <90°, or =90° ? Why? Raise your hand if you know the answer.. 108° 55° x° 59° Example Correct…because x is an obtuse angle it will be greater than 90° The reason you look at that is to make sure that your answer is reasonable…so if you get an answer less than or equal to 90°, you have to question it! 108° 55° x° 59° Example To find the missing measure add up the angles and 55° subtract from 360°. 360-(108+55+59)=x 360 – 222 = x 138 = x Therefore, x = 138° and your answer is reasonable! 108° x° 59° Your Turn In the notes section of your notebook draw the figure and solve for x x° 113° Summary In the notes section of your notebook summarize the key concepts covered in today’s lesson Today we discussed The types of quadrilaterals – you will see this on a test! How to find the missing angle of a quadrilateral! Assignment Quadrilateral Concept Map Follow the directions on the sheet!