00:01
So, here in this question, we have a triangle which look like this.
00:07
So, that is a, b and c and this is small b and this is x and this is small c and this here the this means these two sides making an angle of 88 degree.
00:22
So, we have to find the value of x using cosine rule.
00:32
Cosine, so, solution.
00:35
So, the cosine rule says that law of cosine, it says that that is bc the whole square means the longest side the whole square equal to ac whole square plus ab the whole square minus 2ac 2ab cos theta.
01:04
So, basically it follows like means to derive this law of cosine we can get this from the pythagoras theorem.
01:11
Now, here the bc is what that is x square and ac is what our small c and also in a question the small b is what 40 and the small c is what 4 and cos 88 degree from the trigonometric table it is 0 .035.
01:32
So, it is given now...