how many unique 10 digit numbers can be formed if the number 2 is in the first place and repetition is allowed?

362880 ways

Step-by-step explanation:

Given

10 digits

Required

Number of 10 digits that can be formed if no repetition and 2 must always start;

Since digit 2 must always start and no repetition is allowed, then there are 9 digits left

Digit 2 can only take 1 position

9 digits can be arranged without repetition in 9! ways;

Calculating 9!

Number of arrangement  = 1 * 362880

Number of arrangement  = 362880 ways

i belive those are the ones that are under 90 degreese.

step-by-step explanation:

given that there are two triangles j'k'l' and jkl>

the former is got by dilating the second one.

when drawn on a grid, (graph paper) coordinates of vertices of first triangle is

(6,12)j, (9,6)k and (12,9)l

side jk has length = distance between j and k

=

side j'k'=distance between j' and k'

=

ie j'k'l' has sides 1/3 of that of corresponding sides of jkl.

hence scale factor of 1/3 is used to get j'k'l'from jkl