Open in App
Log In Start studying!

Select your language

Suggested languages for you:

Problem 275

\(\mathrm{D}\) and \(\mathrm{E}\) are respective points of side \(\underline{\mathrm{AB}}\) and \(\underline{\mathrm{BC}}\) of $\triangle \mathrm{ABC}\(, so that \)\mathrm{AD} / \mathrm{DB}=2 / 3\( and \)\mathrm{BE} / \mathrm{EC}=1 / 4 .\( If \)\underline{\mathrm{AE}}\( and \)\underline{D C}$ meet at \(\mathrm{P}\), find \(\mathrm{PC} / \mathrm{DP}\).

Short Answer

Expert verified
The ratio PC/DP is 1:1, meaning the segments PC and DP have equal lengths.
See the step by step solution

Step by step solution

Unlock all solutions

Get unlimited access to millions of textbook solutions with Vaia Premium

Over 22 million students worldwide already upgrade their learning with Vaia!

Step 1: Understand the problem and label the triangle

Draw triangle ABC with points D on AB and E on BC. Mark point P as the intersection of lines AE and DC. We are given the following ratios: AD/DB = 2/3 and BE/EC = 1/4. Our goal is to find the ratio PC/DP.

Step 2: Identify similar triangles

To solve this problem, we will need to identify similar triangles within the figure. Notice that triangles ADP and EDP are similar because they share angle D and angle ADE is congruent to angle EDE. Additionally, triangles BEP and ECP are similar because they share angle E and angle DEC is congruent to angle ECB.

Step 3: Determine ratios of corresponding sides for similar triangles

As triangles ADP and EDP are similar, we can write the following side ratios: \[\frac{AP}{EP} = \frac{AD}{ED}\] And for triangles BEP and ECP, \[\frac{BP}{EP} = \frac{BE}{EC}\]

Step 4: Use given ratios to express ratios in terms of AD and BE

We are given that AD/DB = 2/3 and BE/EC = 1/4. Therefore, \[ED = AD + DB = AD + \frac{3}{2}AD = \frac{5}{2}AD\] And, \[EC = BE + CD = BE + DB + DB = BE + 2DB = BE + (3DB - BE) = 3DB = 3(\frac{3}{2}AD) = \frac{9}{2}AD\] Substitute the values of ED and EC in the ratios found in step 3: \[\frac{AP}{EP} = \frac{AD}{\frac{5}{2}AD} = \frac{2}{5}\] \[\frac{BP}{EP} = \frac{BE}{\frac{9}{2}AD} = \frac{2}{9}\]

Step 5: Apply Ceva's theorem

Ceva's theorem states that for point P inside triangle ABC, lines AP, BP, and CP are concurrent (intersect at a single point) if and only if the ratio product: \[\frac{AP}{PB} \cdot \frac{BP}{PC} \cdot \frac{CP}{PA} = 1\] Using the values found in Step 4, we can determine the ratio PC/DP: \[\frac{AP}{EP} \cdot \frac{DP}{PC} \cdot \frac{CP}{AP} = 1\] \[\frac{2}{5} \cdot \frac{DP}{PC} \cdot \frac{CP}{AP} = 1\]

Step 6: Solve for PC/DP ratio

To find the value of PC/DP, we need to manipulate the equation from Step 5: \[\frac{DP}{PC} = \frac{5}{2} \cdot \frac{AP}{CP}\] Use the equation found in step 4: \[\frac{DP}{PC} = \frac{5}{2} \cdot \frac{2}{5}\] \[\frac{DP}{PC} = 1\] Therefore, the ratio PC/DP is 1:1, meaning the segments PC and DP have equal lengths.

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Access millions of textbook solutions in one place

  • Access over 3 million high quality textbook solutions
  • Access our popular flashcard, quiz, mock-exam and notes features
  • Access our smart AI features to upgrade your learning
Get Vaia Premium now
Access millions of textbook solutions in one place

Join over 22 million students in learning with our Vaia App

The first learning app that truly has everything you need to ace your exams in one place.

  • Flashcards & Quizzes
  • AI Study Assistant
  • Smart Note-Taking
  • Mock-Exams
  • Study Planner
Join over 22 million students in learning with our Vaia App Join over 22 million students in learning with our Vaia App

Recommended explanations on Math Textbooks