If cosA= 1/√17 and cosB = 3/√34, then show that: A+B = 3π/4.




 Answer:

Since, we have been asked to prove the value of A+B = 3π/4 and we know it well that, π=180°
So, 3π/180 = 135°.

We now have to use the formula of cos(A+B) or sin(A+B) because we need to prove the given value of A+B.

For this, we first find out sinA and sinB because without them none of the formulas of double angles can be expanded.

Secondly, to find sinA and sinB, you can either use this fomula, sinA= √(1- cos²A)
Or, cosA= b/h and use Pythagoras theorem to find out p and find the value of sinA using p/h.

Then, you simply solve these questions using basic Mathematics and you get to a solution. Then you need to change the given value into Trigonometric angle with function.

Finally, we will be able to prove the given values!

These formulas might help you solve these question!


All the best!

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