Math Problem Statement

If BD bisects ∠CBE, BC ⊥ BA, m∠CBD = (3x + 25)°, and m∠DBE = (7x − 19)°, find m∠ABD.

Solution

The problem asks to find mABDm \angle ABD under the given conditions:

  1. BD\overline{BD} bisects CBE\angle CBE,
  2. BCBA\overline{BC} \perp \overline{BA} (i.e., ABC=90\angle ABC = 90^\circ),
  3. mCBD=(3x+25)m \angle CBD = (3x + 25)^\circ,
  4. mDBE=(7x19)m \angle DBE = (7x - 19)^\circ.

Let's break this down step by step:

Step 1: Understanding the angle relationships

Since BD\overline{BD} bisects CBE\angle CBE, we know: mCBD=mDBEm \angle CBD = m \angle DBE This gives us the equation: 3x+25=7x193x + 25 = 7x - 19

Step 2: Solve for xx

Solving the equation: 3x+25=7x193x + 25 = 7x - 19 Subtract 3x3x from both sides: 25=4x1925 = 4x - 19 Add 19 to both sides: 44=4x44 = 4x Divide by 4: x=11x = 11

Step 3: Find the measures of CBD\angle CBD and DBE\angle DBE

Substitute x=11x = 11 into the expressions for mCBDm \angle CBD and mDBEm \angle DBE: mCBD=3(11)+25=33+25=58m \angle CBD = 3(11) + 25 = 33 + 25 = 58^\circ mDBE=7(11)19=7719=58m \angle DBE = 7(11) - 19 = 77 - 19 = 58^\circ Thus, mCBE=mCBD+mDBE=58+58=116m \angle CBE = m \angle CBD + m \angle DBE = 58^\circ + 58^\circ = 116^\circ.

Step 4: Find mABDm \angle ABD

Since BCBA\overline{BC} \perp \overline{BA}, we know that ABC=90\angle ABC = 90^\circ. We are looking for mABDm \angle ABD, and because: mABC+mABD+mDBC=180m \angle ABC + m \angle ABD + m \angle DBC = 180^\circ Substitute the known values: 90+mABD+58=18090^\circ + m \angle ABD + 58^\circ = 180^\circ Solve for mABDm \angle ABD: mABD=1809058=32m \angle ABD = 180^\circ - 90^\circ - 58^\circ = 32^\circ

Thus, mABD=32m \angle ABD = 32^\circ.


Would you like more details or further clarification on any steps?

Here are five related questions:

  1. How does the bisector of an angle affect its adjacent angles?
  2. What is the significance of perpendicular lines in geometric angle calculations?
  3. How do you solve linear equations involving angles in geometric figures?
  4. What is the role of supplementary angles in solving for unknown angles in triangles?
  5. How can angle bisectors be used to solve for unknown variables in geometry?

Tip: In geometry problems, clearly identifying known relationships like perpendicularity or bisectors can simplify the solution greatly.

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Math Problem Analysis

Mathematical Concepts

Angle Bisectors
Linear Equations
Geometry

Formulas

Angle bisector theorem
Sum of angles in a triangle = 180°
Perpendicularity implies a right angle (90°)

Theorems

Angle Bisector Theorem
Right Angle Theorem
Supplementary Angles

Suitable Grade Level

Grades 9-11