Question

determine the value of the following without the use of a calculator :
1.1. [2cos]^{2} 15 - 1 =

1.2. if cosA + sinA = x and cosA - sinA = y then write cos2a in terms of x and y
cos2A =

1.3. simplify : sin75
sin(45+30) =

1.4. if cos 32 = x, determine in terms of x :
cos64=

Answer 1

Start by taking the first digit of the first number (2 for 24) and multiplying that by the number directly higher than it, which will give you the first digit(s) of the answer. So for 24 multiplied by 26, it would be 2 (first digit in first number) multiplied by 3 (one digit higher) = 6.

Answer 2

Answer :-

Start by taking the first digit of the first number (2 for 24) and multiplying that by the number directly higher than it, which will give you the first digit(s) of the answer. So for 24 multiplied by 26, it would be 2 (first digit in first number) multiplied by 3 (one digit higher) = 6.