To find perimeter $ P $ use formula:
$$ P = 2 a + 2 b $$After substituting $a = \sqrt{ 98 }\, \text{cm}$ and $b = \sqrt{ 8 }\, \text{cm}$ we have:
$$ P = 2 \cdot \sqrt{ 98 }\, \text{cm} + 2 \cdot \sqrt{ 8 }\, \text{cm} $$ $$ P = 2 \sqrt{ 98 }\, \text{cm} + 2 \sqrt{ 8 }\, \text{cm} $$ $$ P = 25.4558\, \text{cm} $$