Question

WILL FAN AND MEDAL
Use Fundamental Identities​ and/or the Complementary Angle Theorem to find the exact value of the expression. Do not use a calculator. cos70°sin20°+sin 70°cos 20°

Answer 1

so like a first step do you know formulas like sin(a+b) or cos(a+b) or sin(a-b) or cos(a-b) for example ? - check them and will se how will get same result and so will can continue and calculi it without calculator