Question

If the sides of a triangle are in ratio 3 : 7 : 8, then R : r is equal to

• A. 2 : 7
• B. 7 : 2
• C. 3 : 7
• D. 7 : 3

Answer 1

Answer: (B)

7 : 2

Answer 2

Let the sides 3x, 7x and 8x

s = $\frac { a + b + c } { 2 }$ = 9x

D = $\sqrt { s ( s - a ) ( s - b ) ( s - c ) }$

= $\sqrt { 9 \mathrm { x } ( 6 \mathrm { x } ) ( 2 \mathrm { x } ) ( \mathrm { x } ) }$ = $6 \sqrt { 3 } x ^ { 2 }$

R = $\frac { \mathrm { abc } } { 4 \Delta }$ = $\frac { ( 3 x ) ( 7 x ) ( 8 x ) } { 4.6 \sqrt { 3 } x ^ { 2 } }$ =

r = = $\frac { 6 \sqrt { 3 } x ^ { 2 } } { 9 x }$=

\ $\frac { \mathrm { R } } { \mathrm { r } }$=