Hello Jyoti
We got 12.25 by dividing,
and then got 3.5 by taking root of 12.25
Please check the video explanation https://www.teachoo.com/1340/470/Ex-13.4--6---Find-radius-of-a-sphere-whose-surface-area/category/Ex-13.4/
Written on July 4, 2018, 6:10 p.m.