Vector Analysis
I tried breaking the middle term to somehow cancel out the first and last term. is this correct or am I way off?
Application of cross product
Well if we take out area of parlellogram and equate it with 1/2(d1xd2) which we can write as 1/2|d1||d2|sintheta|, i get theta as root(7/9) while the actual answer is cos theta= root (3/10)
Elasticity
my solution has taken the normal formula of U/v = 1/2 x stress x straint to cancel out the equal lengths with which i get the answer 2:1 but the solution they gave, they converted strain = stress/Y and cancelled out Y both sides which makes no sense cause the question says their length is equal and not their Y. Am i wrong or is the solution/answer by nta just incorrect?
A.P.
I solved by first expanding the ap and then eliminating the terms divisible by 3 then i formed 2 different aps (one starting with 8 and the other with 13) each with cd = 15 and summed them up separately. but my answer is wrong whereas the solution given takes the sum of this normal ap first then subtracts it with sum of multiples of 3 in it. i want to understand why my method was wrong?
EM Waves
shouldnt a and c both be correct B has to perpendicualr , no information given about direction of wave
