In atriangle abc the triangles are in ap with common difference alpha ...
Triangle ABC in an Arithmetic Progression
Given that triangle ABC is an arithmetic progression (AP) with a common difference of alpha, we need to find the value of the triangle.
Step 1: Understanding the Problem
To solve this problem, we need to understand the concept of an arithmetic progression and how it relates to the angles of a triangle. We also need to know the value of cos(alpha) in order to find the triangle.
Step 2: What is an Arithmetic Progression?
An arithmetic progression (AP) is a sequence of numbers in which the difference between any two consecutive terms is constant. In this case, the terms of the sequence represent the angles of the triangle.
Step 3: Finding the Common Difference
We are given that the common difference, alpha, is such that cos(alpha) = 21/22. To find the value of alpha, we can use the inverse cosine function:
alpha = arccos(21/22)
Step 4: Finding the Angles of the Triangle
Since triangle ABC is in an arithmetic progression, the angles can be represented as:
A = alpha
B = alpha + alpha = 2alpha
C = alpha + 2alpha = 3alpha
Step 5: Evaluating the Angles
Substituting the value of alpha, we can find the values of the angles:
A = arccos(21/22)
B = 2arccos(21/22)
C = 3arccos(21/22)
Step 6: Simplifying the Angles
We can simplify the expressions for the angles by using the trigonometric identity cos(3theta) = 4cos^3(theta) - 3cos(theta):
A = arccos(21/22)
B = 2arccos(21/22)
C = 3arccos(21/22) = arccos(21/22) + 2arccos(21/22)
Step 7: Simplifying Further
By substituting the value of alpha, we can simplify the expressions for the angles:
A = arccos(21/22)
B = 2arccos(21/22) = arccos(21/22) + arccos(21/22)
C = 3arccos(21/22) = arccos(21/22) + 2arccos(21/22)
Step 8: Evaluating the Angles
By substituting the value of cos(alpha), we can evaluate the expressions for the angles:
A = arccos(21/22) ≈ 0.446 rad
B = 2arccos(21/22) ≈ 0.892 rad
C = 3arccos(21/22) ≈ 1.338 rad
Step 9: Conclusion
Therefore, the angles of triangle ABC are approximately:
A ≈ 0.446 rad
B ≈ 0.892 rad
C ≈ 1.338 rad
To make sure you are not studying endlessly, EduRev has designed Class 11 study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in Class 11.