Triangle ABC is drawn to circumscribe a circle radius 2 cm such that s...
Solution:
Introduction:
Let ABC be a triangle with incenter I, and let the incircle of ABC touch sides BC, CA, and AB at D, E, and F, respectively. Let EF meet BC at X and let DI meet EF at Y. Using properties of tangents to circles, it can be shown that BY = YX = XC.
Given:
Radius of the circle = 2 cm
Length of BD = 4 cm
Length of CD = 3 cm
Area of triangle ABC = 21 cm²
To find:
AB and AC
Solution:
Step 1: Find the perimeter of the triangle ABC
Let s be the semi-perimeter of triangle ABC. The perimeter of triangle ABC is given by:
P = 2s
Step 2: Find the area of triangle ABC
The area of triangle ABC can be found using the formula:
A = sr
where r is the radius of the inscribed circle.
Step 3: Find the inradius of the triangle
The radius of the inscribed circle of triangle ABC is given by:
r = A/s
Step 4: Find the length of AD
The length of AD can be found using the formula:
AD = s - a
Step 5: Find the length of BD and CD
The length of BD and CD can be found using the formula:
BD = s - c
CD = s - b
Step 6: Find the lengths of AB and AC
The lengths of AB and AC can be found using the Pythagorean theorem:
AB² = (s - b)² + r²
AC² = (s - c)² + r²
Step 7: Substitute the given values and solve for AB and AC
Substituting the given values, we get:
s = (4 + 3 + AB + AC)/2 = (7 + AB + AC)/2
A = sr = (s(4+3+AB+AC))/2 = (7s+AB+AC)/2
r = A/s = (7s+AB+AC)/2s
AD = s - a = (7 + AB + AC)/2 - 4 = (1 + AB + AC)/2
BD = s - c = (7 + AB + AC)/2 - 3 = (4 + AB + AC