A/cosA=b/cosB=C/cosC;if b=2 then the area of triangle is?
Solution:
Given, A/cosA=b/cosB=C/cosC
Let b=2
Then, A/cosA=2/cosB=C/cosC
Multiplying all the terms, we get:
A×C×2=cosA×cosB×cosC
Area of the triangle = 1/2×b×h
We know, b=2
Let h be the perpendicular drawn from A to BC.
h=c×sinA
Now, we need to find the value of c.
Using the cosine rule in triangle ABC, we get:
c²=a²+b²-2ab×cosC
Substituting the values, we get:
c²=A²+4-4AcosC/cosA
Now, using the formula of area of a triangle, we get:
Area = 1/2×2×c×sinA
Substituting the values of c and sinA, we get:
Area = 2sinA√(A²+4-4AcosC/cosA)
Now, we have to find the value of sinA.
Using the sine rule in triangle ABC, we get:
a/sinA=b/sinB=c/sinC
Substituting the values, we get:
A/sinA=2/sinB=C/sinC
Now, multiplying all the terms, we get:
A×C×2=sinA×sinB×sinC
Simplifying, we get:
sinA=sqrt[(A²+4-4AcosC/cosA)/(A²+4+4AcosC/cosA)]
Substituting the value of sinA, we get:
Area = 2√[(A²+4-4AcosC/cosA)×(1-cos²C)/(cosA×cosC)]
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.