Incircle of ` A B C` touches the sides BC, CA and AB at D, E and F, respectively. Let `r_1` be the radius of incircle of ` B D Fdot` Then prove that `r_1=1/2((s-b)sinB)/((1+sin(B/2)))`

Incircle of DeltaABC touches the sides BC, AC and AB at D, E and F, respectively. Then answer the following question angleDEF is equal to

Incircle of DeltaABC touches the sides BC, AC and AB at D, E and F, respectively. Then answer the following question The length of side EF is

Let the incircle with center I of A B C touch sides BC, CA and AB at D, E, F, respectively. Let a circle is drawn touching ID, IF and incircle of A B C having radius r_2dot similarly r_1a n dr_3 are defined. Prove that (r_1)/(r-r_1)dot(r_2)/(r-r_2)dot(r_3)/(r-r_3)=(a+b+c)/(8R)

In a triangle ABC, the incircle touches the sides BC, CA and AB at D,E,F respectively. If radius of incircle is 4 unit and BD,CE and AF be consecutive natural numbers. The sum of the cubes of the length of the sides is lambda, then lambda/2079 is ........

In DeltaABC , the incircle touches the sides BC, CA and AB, respectively, at D, E,and F. If the radius of the incircle is 4 units and BD, CE, and AF are consecutive integers, then

In an acute angled triangle A B C , a semicircle with radius r_a is constructed with its base on BC and tangent to the other two sides. r_b a n dr_c are defined similarly. If r is the radius of the incircle of triangle ABC then prove that 2/r=1/(r_a)+1/(r_b)+1/(r_c)dot

Let ABC be a triangle with incentre I and inradius r. Let D, E, F be the feet of the perpendiculars from I to the sides BC, CA and AB, respectively, If r_(2)" and "r_(3) are the radii of circles inscribed in the quadrilaterls AFIE, BDIF and CEID respectively, then prove that r_(1)/(r-r_(1))+r_(2)/(r-r_(2))+r_(3)/(r-r_(3))=(r_(1)r_(2)r_(3))/((r-r_(1))(r-r_(2))(r-r_(3)))

The incircle of Delta ABC touches the sides AB, BC and CA of the triangle at the points D, E and F. Prove that AD + BE +CF=AF+CE +BD=1/2 (The perimeter of DeltaABC )

Let A B C be a triangle right-angled at Aa n dS be its circumcircle. Let S_1 be the circle touching the lines A B and A C and the circle S internally. Further, let S_2 be the circle touching the lines A B and A C produced and the circle S externally. If r_1 and r_2 are the radii of the circles S_1 and S_2 , respectively, show that r_1r_2=4 area ( A B C)dot

Let A B C be a triangle with incenter I and inradius rdot Let D ,E ,a n dF be the feet of the perpendiculars from I to the sides B C ,C A ,a n dA B , respectively. If r_1,r_2a n dr_3 are the radii of circles inscribed in the quadrilaterals A F I E ,B D I F ,a n dC E I D , respectively, prove that (r_1)/(r-1_1)+(r_2)/(r-r_2)+(r_3)/(r-r_3)=(r_1r_2r_3)/((r-r_1)(r-r_2)(r-r_3))