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Grade 12th passAlgebra

if a,b,c are sidesof traingle and a+b=x,a*b=y, x^2-c^2=y then find the ratio of r/R ?
R: circum circle radius
r: incircle radius

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8 Years agoGrade 12th pass
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ApprovedApproved Tutor Answer1 Year ago

To find the ratio of the inradius (r) to the circumradius (R) of a triangle given the conditions a + b = x, ab = y, and x² - c² = y, we can start by analyzing the relationships between the sides of the triangle and the radii.

Understanding the Triangle's Properties

In any triangle, the circumradius (R) and inradius (r) can be expressed in terms of the triangle's area (A) and its semiperimeter (s). The formulas are as follows:

  • R = abc / (4A)
  • r = A / s

Here, s is the semiperimeter, defined as:

s = (a + b + c) / 2

Using Given Conditions

From the problem, we know:

  • a + b = x
  • ab = y
  • x² - c² = y

We can rearrange the third equation to express c in terms of x and y:

c² = x² - y

Thus, c = √(x² - y).

Finding the Semiperimeter

Now, substituting the values of a + b and c into the semiperimeter:

s = (x + c) / 2 = (x + √(x² - y)) / 2.

Calculating the Area

To find the area A, we can use Heron's formula:

A = √[s(s - a)(s - b)(s - c)]

Substituting the values of s, a, b, and c will allow us to express A in terms of x and y.

Finding the Ratio r/R

Now, we can express the ratio r/R:

r/R = (A/s) / (abc / (4A)) = (4A²) / (s * abc).

Substituting the expressions for A and s into this ratio will yield a formula that depends on x and y. After simplification, we can derive the ratio of the inradius to the circumradius.

Final Steps

To finalize the calculation, we would need to substitute the specific values of a, b, and c derived from x and y into the formulas for A, s, and subsequently r and R. However, without specific numerical values for a, b, and c, we can conclude that the ratio r/R will depend on the specific triangle formed by these sides.

In summary, the ratio of the inradius to the circumradius can be derived from the triangle's properties and the relationships between its sides, but the exact numerical ratio will require specific values for a, b, and c. This approach highlights the interconnectedness of the triangle's dimensions and its radii.