Splash Screen. Lesson Menu Five-Minute Check (over Lesson 11–3) Then/Now New Vocabulary Key Concept: Angles of a Quadrilateral Example 1: Find Angle Measures.

Five-Minute Check (over Lesson 11–3)

Then/Now

New Vocabulary

Key Concept: Angles of a Quadrilateral

Example 1: Find Angle Measures

Example 2: Real-World Example: Classify Quadrilaterals

Over Lesson 11–3

Choose the figure after a 180° clockwise rotation about point S.

A.

B.

C.

D.

Over Lesson 11–3

Choose the figure after a 270° clockwise rotation about point A.

A.

B.

C.

D.

Over Lesson 11–3

Which figure does not have rotational symmetry?

A.

B.

C.

D.

Over Lesson 11–3

A. A'(0, 3), B'(–6, 5), C'(1, 5)

B. A'(0, 3), B'(5, 1), C'(–2, 1)

C. A'(0, 3), B'(6, 5), C'(2, 4)

D. A'(0, 3), B'(–5, 1), C'(2, 1)

A triangle has vertices A(0, 3), B(–2, –3), and C(–2, 4). If the triangle is rotated clockwise 90° about point A, what are the new coordinates of the triangle?

You found missing angle measures of a triangle. (Lesson 10–3)

• Find missing angle measures of a quadrilateral.

• Classify quadrilaterals.

• quadrilateral

Find Angle Measures

ALGEBRA Find the value of x in the quadrilateral. Then find each missing angle measure.

The sum of the measures of the angles is 360°.

Let mQ, mR, mS, and mT represent the measures of the angles.

Find Angle Measures

mQ + mR + mS + mT = 360 Angles of a quadrilateral

75 + 4x + 110 + x = 360Substitution

5x + 185 = 360 Combine like terms.

5x + 185 – 185 = 360 – 185 Subtract 185 from each

side.

5x = 175 Simplify.

x = 35 Divide each side by 5.Answer: So, mT = 35° and mR = 4(35) or 140°.

A. x = 4; mA = 4° and mC = 16°

B. x = 5; mA = 5° and mC = 20°

C. x = 40; mA = 40° and mC = 160°

D. x = 104; mA = 104° and mC = 416°

Find the value of x. Then find each missing angle measure.

Classify Quadrilaterals

Answer: parallelogram

Classify the quadrilateral shown using the name that best describes it.

The quadrilateral has both pairs of opposite sides parallel and congruent.

A. square

B. rectangle

C. rhombus and rectangle

D. parallelogram and square

QUILT PATTERN The figure shows a pattern for the border of a quilt. Classify the quadrilaterals used to form the flower and the leaves using the name that best describes them.