How to check in angular template if an object is null in a strict checking option.

You can't change your age it stays the same as soon as you sign up

Hypothesis: volumes of both figures are equal.the volume of  figure 1 is: .the volume of figure 2 is: .since , you can conclude that and . so, .volumes of figures are equal only when an angle in the basis is right (then figures will be the same), in another cases volume of figure 1 is less than volume of figure 2.the hypothesis was not correct in all cases.

You keep on reviving

Imean it could be both ways