Trigonometry formulas

Simplify:
1-2sin²15^o

• sin(30^o)
• sin(15^o)
• cos(30^o)
• cos(15^o)

Simplify:
sin10^ocos15^o-sin15^ocos10^o

• cos(-5^o)
• sin(5^o)
• cos (5^o)
• sin(-5^o)

What is the sum of sines formula?

• sin(a+b)=sina+sinb
• sin(a+b)=sinasinb+cosacosb
• sin(a+b)=sinacosb+sinbcosa
• sin(a+b)=sinacosb-sinbcosa

Which is not a version of the double angle formula for cosines?

• cos²(x)-sin²(x)
• 2cos²x-1
• cos²x+sin²x
• 1-2sin²(x)

Which is the correct form of the addition formula for cosine?

• sin^2x+cos²=1
• a²=b²+c²-2bccosA
• cos(a+b)=cosacosb-sinasinb
• sinA/a=sinB/b=sinC/c

Which of the following is the law of sines?

• sinA/a=sinB/b=sinC=c
• b²=a²+c²-2accosB
• sin(a+b)=sinacosb+sinbcosa
• cos(a-b)=cosacosb+sinasinb