Does matchmaker assign sides by tank type

There are trade offs with a premium tank so the decision to buy one is not as simple as saying 'does it make more money?'

Firstly a premium tank is costly to purchase, the high tier ones with the best earning potential are 7500 to 12000 gold (£30-40) each and there's no point in buying a premium tank without spending another 1000 gold on a 100% crew, you will also need to spend another million silver (2500 gold) to get Ventilation and a Rammer. So that's a layout of approximately £50-60.

Secondly you need to know that the premium tanks are not the best tanks (apart from the Type 59 of course). An equivalent tank of the same tier will generally out perform a premium tank by a small but appreciable margin.

Thirdly, for grinding out silver a premium account effectively doubles your income. Although it only boosts your basic income by 50%, that is before you pay for repairs and ammo which can easily halve your final income, but with premium that 50% bonus to the gross amount works out as about 100% on the net profit. Premium tanks only have a significantly reduced repair cost which is why they're good for grinding silver.

Fourthly you need to be at least an average to good player to really benefit from a premium tank, just turning up and going AFK in a premium tank is only minimally more effective than doing the same in any other tank. You quality of play massively influences your income.

So yes, premium tanks can earn more money, but it's no as simple as buy premium > profit!

The formula for calculating the effective armor rating in world of tanks is:

Armor tickness/cos(impact angle)

With an Angle of > 70% always leading to a ricochet, this leads to this table:

Impact Angle    Effective Armour Thickness
    0°                 100%
   10°                 101.54%
   20°                 106.42%
   30°                 115.47%
   40°                 130.54%
   50°                 155.57%
   60°                 200%
   70°                 292.38%
  > 70°                Ricochet

(source: world of tanks effective armor rating)

Which angle to chose depends a lot on the tank you're driving and how it is armored. But in general, having at least a slight angel towards your opponent is a good idea.

For example, if you're driving a tank with 100mm front armor and 80mm side armor, a 45% angle on both front armor would give you an effective front armor of 141mm and effective side armor of 113mm. In this example having the opponent hit your side at an angle would still give a lower chance of penetration than hitting the front armor at a straight angle.

However if the situation is the same, but the tank you're driving only has 60mm side armor this means the effective rating of the side armor would be 85mm, which means you're giving your opponent an opportunity at an easier penetration, in this case it would be still good to present yourself at an angle, but less than 45%. (a 30% angle in this case would give you 115mm front armor and 120mm side armor)