The sides of the triangular base of a prism are 13 cm ,20cm and 21 cm find the area of its cross section

126sq cm

Step-by-step explanation:

Let s be the semi-perimeter of the triangular base of the prism. Then, 

S = (13 + 20 + 21)/2 cm. = 27 cm. 

Therefore, the area of the prism = √[s(s - a)(s - b)(s - c)] 

= √(27(27 - 13)(27 - 20)(27 - 21)) sq. cm. 

= √(27 × 14 × 7 × 6) sq. cm. 

= 9 × 7 × 2 sq. cm. 

= 63 *2

=126sq cm

answer: because rebecca is 12.5% taller than debbie, she is 112.5% of debbie's height (100% + 12.5% = 112.5%). to ? nd out 112.5% of debbie's height, multiply debbie's height through the decimal equivalent of 112.5% (1.125); 64 × 1.125 = 72 inches. if you chose c, you found what rebecca's height would be if she were 12.5% shorter than debbie (you subtracted on the other hand of added).

step-by-step explanation: