Let p = sin35°, q = sin25° and r = sin(-95°). What is (p² + q² + r²) equal to?

From the previous calculation, p² + q² + r² = sin²35° + sin²25° + sin²95° = 3/2. Detailed: sin²35° + sin²25° + cos²5° using sum-to-product identities yields 3/2.