bellringer 67° x°x° y°y° x = ? y = ? this is a base angle of an isosceles triangle. it must...

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BELLRINGER 67° x = ? y = ? This is a base angle of an isosceles triangle. It must measure 67° 67 Find x by using LP. 67 + x = 180. -67 -67 x = 113° Lastly, use TAS to find y. 67 + 90 + y = 180 y = 23°

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Page 1: BELLRINGER 67° x°x° y°y° x = ? y = ? This is a base angle of an isosceles triangle. It must measure 67° 67 Find x by using LP. 67 + x = 180. -67 -67 x

BELLRINGER

67°

y°x = ?

y = ?

This is a base angle of an isosceles triangle. It must measure 67°

67

Find x by using LP. 67 + x = 180.

-67 -67

x = 113°

Lastly, use TAS to find y. 67 + 90 + y = 180

y = 23°

Page 2: BELLRINGER 67° x°x° y°y° x = ? y = ? This is a base angle of an isosceles triangle. It must measure 67° 67 Find x by using LP. 67 + x = 180. -67 -67 x

What is the maximum number of congruent angles in a Scalene Triangle? In an equilateral triangle, we already

showed that all 3 angles are congruent. (60, 60, 60).

In an isosceles triangle we showed that TWO angles are congruent, the base angles.

Thus, there can be NO angles congruent in a scalene triangle, otherwise it would be isosceles or equilateral.

Page 3: BELLRINGER 67° x°x° y°y° x = ? y = ? This is a base angle of an isosceles triangle. It must measure 67° 67 Find x by using LP. 67 + x = 180. -67 -67 x

Triangle Angle-Side Relationships

You will find that the largest angle in a triangle corresponds to the longest side, and the smallest angle corresponds to the shortest side.

For example, name the sides from shortest to longest!

80

43

57

p

q

r68

52

60

xy

z

q, p, r z, x, y

Page 4: BELLRINGER 67° x°x° y°y° x = ? y = ? This is a base angle of an isosceles triangle. It must measure 67° 67 Find x by using LP. 67 + x = 180. -67 -67 x

In Other Words,

LARGEST

LONGEST

SMALLEST

SHORTEST

Page 5: BELLRINGER 67° x°x° y°y° x = ? y = ? This is a base angle of an isosceles triangle. It must measure 67° 67 Find x by using LP. 67 + x = 180. -67 -67 x

What is a median?

The median of a triangle connects a vertex to the opposite side’s midpoint.

X

Y

Z The three medians of any triangle are concurrent at the CENTROID.

Page 6: BELLRINGER 67° x°x° y°y° x = ? y = ? This is a base angle of an isosceles triangle. It must measure 67° 67 Find x by using LP. 67 + x = 180. -67 -67 x

Special segments of a triangle Can you find the altitude, angle

bisector, median, perpendicular bisector, and midsegment??

Altitude

Angle Bisector

Median

Perpendicular Bisector

Midsegment

Page 7: BELLRINGER 67° x°x° y°y° x = ? y = ? This is a base angle of an isosceles triangle. It must measure 67° 67 Find x by using LP. 67 + x = 180. -67 -67 x

Summarize our findings . . .

The angle bisectors of a triangle are concurrent at the incenter. The circle centered at the incenter is inscribed in the triangle.

The perpendicular bisectors of a triangle are concurrent at the circumcenter. The circle centered at the circumcenter circumscribes the triangle.

The altitudes of a triangle are concurrent at the orthocenter. (We will investigate the orthocenter after break).

The medians of a triangle are concurrent at the centroid. The centroid is the center of mass of the triangle.

Page 8: BELLRINGER 67° x°x° y°y° x = ? y = ? This is a base angle of an isosceles triangle. It must measure 67° 67 Find x by using LP. 67 + x = 180. -67 -67 x

Picture it all together . . .

A

DC

B

A = altitudes

B = angle bisectors

C = medians

D = perpendicular bisectors

Page 9: BELLRINGER 67° x°x° y°y° x = ? y = ? This is a base angle of an isosceles triangle. It must measure 67° 67 Find x by using LP. 67 + x = 180. -67 -67 x

Hiding the lines . . .

A

DC

B

A = altitudesB = angle bisectorsC = mediansD = perpendicular bisectors