Given: klmn is a parallelogram, ka − angle bisector of ∠k la − angle bisector of ∠l prove: m∠kal = 90°

sum of two adjacent angles of parallelogram is 180

so angle K + angle L = 180

as AK bisects angle K and LA bisects angle L

so, angle AKL + angle ALK = 180 /2 = 90

in triangle AKL,

angle AKL + angle ALK+angle KAL = 180(sum of all angles in triangle = 180)

so, from above two equations,

angle KAL = 90

wuts the answer its not sum of angles theorem but its 180 º and either

Complementary angles, consecutive angles of parallelogram supplementary, or exterior angles theorem.

Step-by-step explanation:

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for